We Need You… to Measure Precipitation!

Are you interested in the weather and science? Do you go outside, wear clothes, or do anything else that is affected by the weather? If so, we want YOU to measure and report precipitation.

The Community Collaborative Rain, Hail, and Snow Network (CoCoRaHS, https://www.cocorahs.org/) is a volunteer network of backyard weather observers of all ages and backgrounds working together to measure precipitation (rain, hail, and snow) in their neighborhoods and communities. All you need to do to participate is have an enthusiasm for watching and reporting weather conditions. More information on CoCoRaHS is here: https://www.cocorahs.org/Content.aspx?page=aboutus#signup. You can sign up for CoCoRaHS here: https://www.cocorahs.org/Application.aspx.

Why we need observers

The National Weather Service operates a high-quality network of weather stations measuring precipitation, but the network is too sparse to capture the often-high variability of precipitation across Illinois. CoCoRaHS observations help fill those gaps. The map below shows an example of how important CoCoRaHS observations are to capturing rainfall across the Land of Lincoln. In just this recent storm event, rainfall totals around the Bloomington-Normal area ranged from 1.69 inches to 0.70 inches. These CoCoRaHS reports are vital for monitoring and predicting drought conditions, potential flooding, and other weather and climate related issues.

Map of daily CoCoRaHS observations in central Illinois from March 23rd.

We are nearing the end of the CoCoRaHS March Madness recruiting period, and Illinois has fallen behind other states in the region. While we have welcomed 37 new CoCoRaHS observers in Illinois this month, we’re trailing Indiana (38), Ohio (89), and Wisconsin (94). We can’t lose to Indiana!

CoCoRaHS volunteers are the largest single source of daily precipitation observations in the U.S.  In 2022 CoCoRaHS observations accounted for two-thirds of all U.S. daily precipitation observation archived by the National Centers for Environmental Information. The more observers participating in CoCoRaHS, the better we can monitor and study precipitation across Illinois. As the map below shows, we’re particularly missing new observers in central Illinois. However, no matter where you are in the state, please consider joining Co CoRaHS and contributing to citizen science in Illinois.

New CoCoRaHS observers in Illinois.

What benefits are there in volunteering? 

Participating in CoCoRaHS is an easy and fun way to make important contributions to science and community resilience. By providing daily observations, you help to fill in a piece of the weather puzzle that affects many across your area in one way or another. CoCoRaHS is also a great educational opportunity for youth and adult learning. Having a CoCoRaHS station in schools help students learn about weather, how it’s measured, and how it differs from one place to another.

How can I sign up for CoCoRaHS?

To sign up, visit this page: https://www.cocorahs.org/Application.aspx. Becoming a CoCoRaHS observer takes just 5 minutes and makes a huge difference in your community and state. 

What if I have questions?

If you have any questions, concerns, or feedback on CoCoRaHS please reach out to the State Climatologist Trent Ford (twford@illinois.edu, 217-244-1330) or Illinois CoCoRaHS Coordinator Steve Hilberg (hberg@illinois.edu), 217-377-6034.

Mild February Wraps up a Weak Winter

The preliminary statewide average February temperature was 35.1 degrees, 4.0 degrees above the 1991–2020 average and tied for the 18th warmest on record going back to 1895. The preliminary statewide average total February precipitation was 3.03 inches, 0.92 inches above the 1991–2020 average and the 17th wettest on record statewide.    

Data are provisional and may change slightly over time.

Persistently Mild February

Climatologically, February is the second coldest month statewide after January. February in 2022 and 2021 were much colder than normal, but that trend was broken this year. Figure 1 shows daily temperature departures from normal in Galesburg in February. More than two-thirds of February days in Galesburg were warmer than normal, following a much warmer than normal January.

Figure 1. Daily February average temperature departures in Galesburg.

February average temperatures ranged from the high 20s in northern Illinois to the mid-40s in southern Illinois, between 2 and 8 degrees above the 1991–2020 normal (Figure 2). Several stations saw daily high temperatures in the 70s last month, including 74 degrees in Williamson County and 70 in Coles County. Meanwhile, a brief period of extreme cold at the start of the month pushed stations in northern Illinois well below zero, including nighttime lows of -14 degrees in Kane County and -13 degrees in Jo Daviess County. Overall, the warmest place in the state last month was Carbondale, with an average temperature of 44.1 degrees, and the coldest place in the state was Stockton in Jo Daviess County with an average temperature of 25.2 degrees.

The mild weather in February broke 17 daily high maximum temperature records and 11 daily high minimum temperature records. No daily low maximum or daily low minimum temperature records were broken last month.

Figure 2. Maps of (left) February average temperature and (right) February average temperature departures from normal.

Overall, the preliminary statewide average February temperature was 35.1 degrees, 4.0 degrees above the 1991–2020 average and tied for the 18th warmest on record going back to 1895.

Where Was Winter?

February wrapped up a very mild climatological winter season, with only a handful of cold air outbreaks and below normal snowfall for most of the state. The near record cold around Christmas pushed December slightly cooler than normal statewide, but the 6th warmest January on record and a top 20 warmest February on record pushed climatological winter average temperatures from somewhat to much warmer than normal.

The 2022–2023 climatological winter average temperatures ranged from the high 20s in northern Illinois to the low 40s in southern Illinois, between 2 and 6 degrees above normal (Figure 3). Overall, the preliminary statewide average winter temperature was 33.1 degrees, 4.9 degrees above the 1991–2020 normal and tied with the 2019–2020 season for the ninth warmest on record.  

Figure 3. Maps of (left) winter average temperature and (right) winter average temperature departures from normal.

With respect to the long-term historical record, the 2022–2023 winter season was unusually warm. However, the season is part of a long-term warming trend that is larger in winter than in any other season across Illinois. Winter warming is one of the most consistent impacts of anthropogenic climate change in Illinois, driven by human greenhouse gas emissions.

As Figure 4 shows, the statewide average winter temperature has increased by about 0.20 degrees per decade since 1895, and the average winter temperature over the last 30 seasons is about 2 degrees warmer than the 20th century average. One of the consequences of this long-term warming trend is a higher chance of warm winters that would be considered unusual based on the 20th century numbers. For example, six of the top 10 warmest winters on record in Illinois have occurred since 2001–2002. 


Figure 4. Plot shows statewide average winter temperature in Illinois (blue line), the long-term trend in winter average temperature (black line), the average winter temperature over the last 30 seasons (green line) and the 20th century average (red line).

Wetter February, Again

February is one of the climatological driest months of the year; however, the shortest month has come with much wetter weather in recent years, and this year followed that pattern. Total February precipitation ranged from around 2 inches in south-central Illinois to over 4 inches in southern Illinois (Figure 5). The Interstate 70 corridor between St. Louis Metro East and Effingham was near normal to half an inch drier than normal, while most areas north and south were 1 to 3 inches wetter than normal.

Two CoCoRaHS observers in Iroquois County–one in Cissna Park and the other in Milford–observed over 5.5 inches of total precipitation last month, and observers in McLeansboro in Hamilton County and LeRoy in McLean County also recorded more than 5 inches of total precipitation. Meanwhile, many stations between Belleville to Effingham recorded less than 1 inch for the month. Last month was the second wettest February on record in Rockford, third wettest on record in Freeport, fourth wettest on record in Quincy, the seventh wettest on record in Bloomington, and the eighth wettest on record in Chicago and Moline.

Figure 5. February total precipitation (left) and February precipitation departure from normal (right).

Our wet winter eradicated all drought across the state, and the Feb. 28 U.S. Drought Monitor map is completely empty for the first time since June 2020. Drought recovery in southern Illinois was particularly remarkable given that each of the south seven counties were in severe or extreme drought on Dec. 1.

The southeast Illinois climate division experienced its seventh driest climatological fall on record, but then had what is likely going to be a top three wettest winter on record (Figure 6). While drought recovery is always a good thing, the kind of rapid flip in extremes, in this case from extremely dry to extremely wet, is less than ideal.

Figure 6. Maps show total precipitation departures from normal for (left) fall 2022 and (right) winter 2022–2023.

February Adds to Snow Deficits

February–along with January–is one of the snowiest months of the year climatologically across the state. However, this past month just added to existing snowfall deficits everywhere north of Interstate 64. Below normal snowfall in January and February is typically due to either excessively mild temperatures that result in more rain than snow, or excessively dry conditions that reduce precipitation overall. This past month fell into the former category, with most areas of the state seeing above normal February precipitation, most of which fell as rain or non-accumulating snow.

Overall, only the areas north of Interstate 72 saw any measurable snowfall last month, with totals ranging from less than half an inch from Adams County to Iroquois County up to 12 inches in far northwest Illinois (Figure 7). All but the northwest tip of the state saw below normal snowfall to the tune of 2 to 8 inches less than expected.

Figure 7. Maps show (left) total February snowfall and (right) February snowfall departure from normal.

Some of the more impressively weak snowfall totals in February included 0.1 inches in Peoria (fourth lowest on record). Both Springfield and Champaign only recorded trace snowfall for the entire month, meaning no snowfall accumulated to the point it could be measured at greater than or equal to 0.1 inches. Last month was only the sixth February on record in Springfield and the fifth February on record in Champaign with no measurable snowfall; both records go back to the early 1900s.

Each of the three months that comprise climatological winter had below normal snowfall for most of the state, and snowfall deficits were particularly large in central and northern Illinois (Figure 8). The 2022–2023 winter snowfall totals ranged from less than 4 inches in parts of central Illinois to just over 25 inches in far northwest Illinois. Much like for February, winter snowfall was near normal for just the northwest tip of the state, 1 to 5 inches less than normal in southern Illinois, and 10 to 20 inches less than normal in central and northeast Illinois. The 2022–2023 winter season was the fifth least snowy on record in Springfield and the seventh least snowy in Champaign.

Figure 8. Maps show (left) total winter snowfall and (right) winter snowfall departure from normal.

March & Spring Outlooks

March is the first month of climatological spring, and the first month we typically begin to see signs of spring. Of course, our mild winter has given us sneak peaks to spring already in February, which make the current Climate Prediction Center outlooks more interesting.

The CPC temperature outlooks lean colder than normal across most of the state, suggesting our unseasonably mild weather may be on hiatus for the third month of the year (Figure 9). One ramification of a cold March for agriculture and spring growth could be a slowdown to our rapid progression toward spring phenology and flowering. Projections of very early spring greenup across the Midwest give heartburn to tree fruit and berry growers and gardeners alike who want to avoid untimely spring freeze damage. Precipitation outlooks for March are leaning to likely wetter than normal, possibly continuing our wet streak from January and February.

Figure 9. Climate Prediction Center (left) temperature and (right) precipitation outlooks for March.

The spring season outlooks (March–May) show closer to equal chances of above and below normal temperatures, suggesting the colder weather potential for March may not bleed into April or May. Most folks would prefer not to repeat the cool and cloudy April we had in 2022. Meanwhile, the green blob in the eastern Midwest persists in the spring outlooks (Figure 10). Soils in most of the state are bordering between being in good shape and being a tad too wet. Wetter than normal conditions in spring could make for some challenges for spring planting and other fieldwork, which have become a perennial problem for southern Illinois especially.

Figure 10. Climate Prediction Center (left) temperature and (right) precipitation outlooks for March through May.

A Very Mild Start to 2023

The preliminary statewide average January temperature was 33.8 degrees, 7.1 degrees above the 1991–2020 average and the 6th warmest on record going back to 1895. The preliminary statewide average total January precipitation was 2.72 inches, 0.41 inches above the 1991–2020 average and the 31st wettest on record statewide.    

Data are provisional and may change slightly over time.

Where is Winter?

January brought widespread and persistent mild weather, with temperatures regularly 5 to 10 degrees above normal and a few days 15 to 20 degrees above normal. Figure 1 shows daily average temperatures last month in Ottawa. Only three out of 31 January days had below normal temperatures in Ottawa, and each of the first 26 days of the month were warmer than normal.

Figure 1. Daily January average temperature departures in Ottawa

Although temperatures were not warm by any means, they were noticeably milder than expected in the first month of the year. January average temperatures ranged from the mid-20s in northwest Illinois to the low 40s in southern Illinois, between 5 and 12 degrees above normal (Figure 2). Last month was the fifth warmest January on record in Peoria and Carbondale, the sixth warmest on record in Chicago, and the seventh warmest on record in Moline, Springfield, and St. Louis. Following long-term warming trends, the nighttime low temperatures last month were particularly unusual. The average nighttime low temperature in Peoria in January was the third highest on record.

Overall, the preliminary statewide average January temperature was 33.8 degrees, 7.1 degrees above the 1991–2020 average and the sixth warmest on record going back to 1895.

Figure 2. Maps of (left) January average temperature and (right) January average temperature departures from normal.

Wetter January, but still not much snow

August 2022 was the last month that was wetter than normal statewide. January is not typically a wet month, but relative to its spring and summer counterparts, this past month brought wetter weather to most of the state. January’s total precipitation ranged from around 2 inches in west-central Illinois to over 7 inches in far southern Illinois. Most parts of northern and southern Illinois were between 0.5 and 2 inches wetter than normal, while much of central Illinois was near to 0.5 inches drier than normal last month (Figure 3). Overall, the preliminary statewide average total January precipitation was 2.72 inches, 0.41 inches above the 1991–2020 average and the 31st wettest on record statewide.

Figure 3. Maps show (left) January total precipitation and (right) January precipitation departure from normal.

The milder January temperatures kept heavy snow at bay for most of the month. January snowfall totals ranged from around 3 inches in southern and south-central Illinois to just under 12 inches in northeast Illinois. Only southern and parts of northeast Illinois had near to above normal snowfall, while the rest of the state had 1 to 6 inches below normal snowfall for the month. The general lack of sizeable January snowfall added to November and December deficits. Season-to-date snowfall remains above normal in southern Illinois, but 3 to 13 inches below normal in central and northern Illinois (Figure 4).

Figure 4. Maps show (left) January snowfall totals (middle) January snowfall departures from normal and (right) winter season to date snowfall departures.

Outlooks

February marks the last month of winter, and likely our last chance for significant snowfall, especially in central and southern Illinois. Climate Prediction Center outlooks for February lean to warmer and wetter than normal conditions, as the atmosphere hangs on to the signal of a quickly weakening La Niña (Figure 5). Odds of wetter than normal conditions are particularly high in far southern Illinois, a region that experienced a very wet February last year.

Figure 5. Maps show (left) temperature and (right) precipitation outlooks for February.

Meanwhile, outlooks for the three-month period between February and April are also leaning to likely wetter than normal statewide, but with equal chances of above or below normal temperatures (Figure 6). The consistent signal of wetter than normal conditions for the end of winter and start of spring would continue making up for precipitation deficits from last fall; however, it also means we’ll need to keep our eye on the potential for excessive wetness and flooding this spring.

Figure 6. Maps show (left) temperature and (right) precipitation outlooks for February.

2022 was Cooler and Drier than Normal

Illinois was both cooler and drier than the 1991–2020 normal in 2022. The statewide average annual temperature was 52.0 degrees, 0.6 degrees below normal and tied for the 51st warmest on record. Statewide average total precipitation in 2022 was 37.24 inches, 3.51 inches below normal and the 61st driest year on record.

2022 Temperatures

Following the second warmest December on record statewide, temperatures moderated quite a bit to start 2022. January and February average temperatures were 4.5 degrees and 3.2 degrees below the 1991–2020 normals, respectively. Spring was a mixed bag, with a very warm March and May split by an April that was nearly 3 degrees colder than normal. A hot start to summer pushed June 1.3 degrees above normal statewide, while July was only 0.3 degrees warmer than normal and August’s average temperature equaled the normal. Fall was very pleasant, as September and November were both just slightly warmer than normal, while October was 1.3 degrees colder than normal statewide. A December full of wild temperature swings ended just over 1 degree colder than normal to cap off 2022.

Overall, the statewide average annual temperature was 52.0 degrees, 0.6 degrees below normal (Figure 1). However, because Illinois has experienced a 100+ year warming trend as part of human-caused climate change, the statewide average annual temperature was still 0.4 degrees above the 20th century average, and 2022 tied for the 51st warmest on record statewide.

Figure 1. Plot shows 2022 statewide monthly average temperature (black line) and temperature departures from the 1991–2020 normal (red and blue bars).

Figure 2 shows 2022 average temperatures and departures from normal across the state. Average temperatures ranged from the low 40s in northern Illinois to the low 50s in southern Illinois. Most of the state was within 1 degree of the 30-year normal, while part of western Illinois was between 1 and 2 degrees colder than normal in 2022.

Figure 2. Maps show 2022 annual average temperature (left) and average temperature departures from the 1991–2020 normal (right).

The year 2022 was the 34th warmest on record in Chicago, 27th warmest on record in St. Louis, 45th warmest on record in Peoria, 50th warmest on record in Rockford, and 48th warmest on record in Moline. The year was also the 60th coolest on record in Springfield, 52nd coolest on record in Quincy, and 39th coolest on record in Carbondale. Bean Ridge in Alexander County was the warmest point in the state in 2022 with an average temperature of 59.5 degrees. Elizabeth in Jo Daviess County was the coldest point in the state last year with an average temperature of 46.6 degrees.

Table 1 shows the number of daily weather records broken at Illinois Cooperative Observer stations in each month of 2022. May led with the highest number of high daily maximum and high daily minimum temperature records, with over 150 of each. Three stations in Illinois broke their all-time May high maximum temperature records in 2022, including a 96-degree high in Rock Island and a 99-degree high in Chenoa. Eleven stations also broke their all-time May high minimum temperature records in 2022, including an 80-degree low temperature in Rock Island and a 74-degree low in Peoria.

The heatwave that broke so many daily weather records across Illinois was remarkable in many ways. First, it occurred in the first half of May, while most May temperature records are set in the latter half of the month. The heat itself was extreme with most places in the state experiencing multiple days with high temperatures in the mid- to upper 90s. Lastly, the heat arrived very quickly and followed a prolonged period of cooler weather in April and early May. A rapid change from cool to hot weather, especially early in the warm season, is associated with an elevated risk of heat-related health impacts.

The Excess Heat Factor (EHF) is a metric used to account for the intensity of a heat wave and how well an area was acclimated (or not acclimated) to the heat ahead of the heat wave. Figure 3 shows all heat waves on record in Rockford, expressed as their EHF value, with higher values indicating more extreme heat waves. Because of its intensity in absolute temperature and compared to the prior cool period in April, the May 2022 heat wave had the highest EHF value of any heat wave on record in Rockford.

Figure 3. Every heat wave on record in Rockford expressed as the Excess Heat Factor. Higher values indicate more intense heat waves.

Milder temperatures in April, October, and November also resulted in dozens of low maximum and low minimum temperature records broken across the state in 2022. However, three times as many high maximum or high minimum temperature records (791) were broken last year in Illinois as low maximum or low minimum temperature records (247).

Table 1. Table shows the number of daily local weather records in 2022 by month and variable.

There were also 538 daily total precipitation records broken across Illinois in 2022. Daily precipitation records broken were somewhat equally spread among months, but July led with 90 records.

2022 Precipitation

Calendar year 2022 began with a very dry January, with less than 50 percent of normal precipitation statewide. February and March were 1.04 inches and 1.42 inches wetter than normal, respectively, making for wet soils heading into the spring. While April was slightly drier than normal statewide, many places in the state had a double-digit number of days with measurable rain. Macomb, for example, had 25 out of 30 April days with measurable rainfall, but was still drier than normal for the month. May was slightly drier than normal, and June was nearly 2 inches drier than normal statewide. Meanwhile, July and August were both wetter than normal, followed by all three fall months with below normal precipitation. December wrapped up 2022 just slightly drier than normal statewide (Figure 4).

Overall, statewide average total precipitation in 2022 was 37.24 inches, 3.51 inches below normal and the 61st driest year on record.

Figure 4. 2022 monthly total precipitation as a departure from the 1991–2020 normal.

Much like past years, the statewide preciptiation statistics are not representative of all places in Illinois. Calendar year 2022 was somewhat to much drier than normal in most of central and southern Illinois, but wetter than normal in areas that experienced extreme rainfall, such as the St. Louis Metro East and far northern Illinois. Last year was the 14th driest on record in Mt Vernon, the 50th driest on record in Champaign, and the 41st driest on record in Moline; however, it was also the 30th wettest on record in Edwardsville and the 9th wettest on record in Freeport.

Figure 5 shows the spatial variability of 2022 precipitation in more detail. Total precipitation in 2022 ranged from nearly 50 inches in far southern Illinois to less than 35 inches across much of north-central Illinois. Large parts of far nothern and south-central Illinois were 1 to 5 inches wetter than normal last year, while much of central and far southern Illinois were 1 to 8 inches drier than normal.

Figure 5. Maps show (left) total precipitation and (right) precipitation departures in 2022.

The long-term Cooperative Observer station in Effingham recorded 56 inches of precipitation in 2022, making Effingham the wettest point in the state last year. Meanwhile, CoCoRaHS citizen science observers in LeRoy in McLean County and Mansfield in Champaign County recorded just 26 inches of precipitation in 2022. The year 2022 was the 21st driest on record in Peoria with just 28.75 inches (76 percent of normal).

2022 Severe Weather

Last year was a mixed bag for severe weather. Most of our 102 counties were affected by strong wind, hail, or tornado events last year (Figure 6). Overall, the NOAA Storm Prediction Center showed 34 tornado reports, 104 hail reports, and 535 wind reports statewide in 2022. The 34 tornado reports in 2022 were well less than the 80 reports noted in 2021 and were the fewest tornado reports in Illinois since 2007.

Figure 6. NOAA Storm Prediction Center report locations in 2022. Wind reports are shown in blue, hail in yellow, and tornado in red. Data are available at: https://www.spc.noaa.gov/climo/online/monthly/states.php?month=00&year=2022&state=IL.

Extreme precipitation and resultant flooding have become a mainstay in Illinois. Last year brought several very heavy precipitation events across the state. Among these events was a series of storms in the St. Louis area on July 26, producing several inches of rain in just a few hours. Parts of Cahokia Heights and Belleville caught 7 to 8 inches of rain in less than eight hours, causing widespread flooding (Figure 7). Based on state estimates of rainfall intensity probabilities, these totals in the Belleville area exceeded the estimated 0.2 percent annual exceedance, meaning this type of event has a 0.2% chance of occurring in any given year (https://www.weather.gov/lsx/July262022Flooding).

Just two weeks later, a swath of east-southeast Illinois between Effingham and Olney saw 7 to 10 inches of rain in less than 24 hours. The intense rainfall, centered over Newton in Jasper County, caused widespread flooding in nearly mature corn and soybean fields and riverine flooding along the Little Wabash and Embarras Rivers. Days later, a series of strong storms produced up to 11 inches of rain in less than 48 hours in parts of Jo Daviess and Stephenson counties in northwest Illinois. The rain inundated roads, flooded homes in and around Freeport, and caused flooding along the Pecatonica River (https://www.weather.gov/dvn/summary_080822).

Overall, 2022 brought its own set of unique conditions and weather. Despite daily and monthly variability in temperature and precipitation, most of the state was a bit cooler and drier than the 1991-2020 normal last year.