Category: Seasonal Outlooks

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Spring Begins with a Very Warm March

The statewide average March temperature was 47.7°F, 6.3° above the 1991-2020 normal for March and the 7th warmest March on record statewide. The statewide average total March precipitation was 2.76 inches, 0.18 inches below normal and the 58th driest March on record statewide.

March Temperatures Start and End Like a Lamb

March temperatures had ebb and flow that is typical of spring in Illinois, yet most days last month were 5 to 25 degrees warmer than normal, as shown by daily temperatures and departures in Elgin (Figure 1). The middle part of the month featured a particularly large temperature swing as a powerful cold front moved through the region. Average temperatures in Elgin dropped from nearly 70 degrees on March 15 to 22 degrees on March 17.

Figure 1. Daily March average temperatures and departures in Elgin.

March average temperatures ranged from the low 40s in northern Illinois to the mid-50s in southern Illinois, between 2 and 7 degrees above normal (Figure 2). Multiple waves of late spring-like weather brought temperatures reaching well into the 80s across the state, including 83 in Quincy and Decatur. Very cold weather, while fleeting, did bring temperatures well below freezing across the state, including nighttime low temperatures of 10 degrees in Lincoln and 12 degrees in Rockford. The coldest place in the state last month was Elgin with an average of 40.9 degrees, while the warmest was Smithland Lock and Dam in Massac County with an average of 53.1 degrees.  

The milder weather broke 71 daily high maximum temperature records in Illinois and 13 daily high minimum temperature records. Meanwhile, no daily low minimum or low maximum temperature records were broken in Illinois last month.

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

Active March with Plenty of Severe Weather

March is the transition month between the normally driest time of the year in the winter and the normally wettest time of the year between April and July. Consequently, we have experienced years where March was extremely dry (only 1.13 inches in 1981) and those that were very wet (6.30 inches in 1973). This year March was only slightly wetter than normal statewide, but with some large gradients across the state.

Total precipitation ranged from less than 1.5 inches in far southwest Illinois to over 8 inches in northeast Illinois. The northern half of the state was 1 to 4 inches wetter than normal last month, while most areas south of Interstate 64 were 1 to 3 inches drier than normal (Figure 3).

Figure 3. March total precipitation (left) and March precipitation departure from normal (right).

While severe weather, including thunderstorms, strong winds, hail, and tornadoes, occur every month in Illinois, they tend to be most common between March and July. An active storm track and abundant moist, warm air from the Gulf of Mexico produced multiple severe weather outbreaks in March across the Midwest. In all, there were 58 tornado warnings issued in Illinois, the most on record for March (Figure 4). The NOAA Storm Prediction Center lists 33 tornado reports in Illinois last month, which may be adjusted before a final number is released. Included in these reports is a confirmed EF-2 tornado that caused significant damage to Neoga High School in Cumberland County on March 15, and multiple tornadoes that damaged or destroyed buildings in Douglas County on March 30.

Figure 4. Tornado warning frequency in March by year across Illinois. Graph is courtesy of the Iowa Environmental Mesonet: https://mesonet.agron.iastate.edu/.

As is the case in most years, March precipitation came in many forms, including snow. However, measurable snowfall was mostly contained to the northern third of the state. Monthly snowfall totals in those places that were able to measure the snow ranged from around 2 inches in the Quad Cities region to over 7 inches in parts of Knox County and Boone County in western and northern Illinois, respectively.

April and Early Growing Season Outlooks

Climatological spring starts with March, but most folks associate spring more with April and May, as weather in Illinois begins to consistently feel springlike. The outlook for April through June shows best chances of warmer and wetter than normal weather for much of Illinois. Most noteworthy is the warm and dry signal that dominates the mountain west and western plains in the first half of the growing season.

Figure 5. Climate Prediction Center (left) temperature and (right) precipitation outlooks for April through June.
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January Brought Winter Weather of Yore

The preliminary statewide average January temperature was 22.3 degrees, 4.4 degrees below the 1991-2020 average and tied for the 34th coldest on record going back to 1895. The preliminary statewide average total January precipitation was 1.25 inches, 1.06 inches below the 1991-2020 average and tied for the 32nd driest on record statewide.

Data are provisional and may change slightly over time.

Is this what winter used to be? 

All four of Illinois’ distinct seasons are getting warmer thanks to human-caused climate change; however, winter is warming far faster than the other seasons. As a result, we have experienced many more mild winters in recent decades; and this trend made last month’s persistently cold weather seem particularly extreme. Daily temperatures and departures from normal in Quincy show much of the first and third weeks of the month had temperatures that were consistently 5 to 30 degrees below normal (Figure 1).

Figure 1. Daily January average temperature departures in Quincy.

January average temperatures ranged from the high teens in northwest Illinois to the low 30s in southern Illinois, between 2 and 8 degrees below normal. Persistent snowpack in southern Illinois helped depress temperatures farther below normal than in relatively snow-less northern Illinois (Figure 2). The warmest point in the state last month was Du Quoin at 31.7 degrees, and the coldest point in the state was Stockton at 16.9 degrees. The few warm spells in January broke 10 daily high maximum temperature records. The extreme cold in the middle of the month broke 23 daily low maximum temperature records and 15 daily low minimum temperature records, including -20 degrees in Springfield.

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

Overall, the preliminary statewide average January temperature was 22.3 degrees, 4.4 degrees below the 1991-2020 average and tied for the 34th coldest on record going back to 1895.

Snowy Southern Illinois

Depending on who you talk to, January 2025 was either a very active winter weather month or quite a boring one. An active storm track setup across the southern half of the state in the first week of January, pushing multiple winter storms through the state, which produced multiple rounds of heavy snow mostly along and south of Interstate 70. The result was a strong gradient of snowfall opposite of what is typical for this time of the year, with more in southern Illinois than northern Illinois.

January total snowfall ranged from over 12 inches in south-central Illinois to less than 1 inch in northwest Illinois. Much of the southern half of the state had 1 to 8 inches more snowfall than normal in January, while northern Illinois racked up a 1-to-8-inch snowfall deficit (Figure 3). Last month was the fifth snowiest January on record in Fairfield with 15.6 inches and the snowiest since 1996. Meanwhile, Moline had only 2.3 inches of snow in January, the lowest amount since 2018 and fourth lowest there since 1989.

Figure 3. Maps of (left) January total snowfall and (right) January snowfall departures from normal

Other than a couple of noteworthy snow and ice events, January was otherwise mostly dry across Illinois. Total January precipitation ranged from just over 5 inches in far southern Illinois to less than a quarter of an inch in far northwest Illinois. Most of northern and central parts of the state were around 1 to 2 inches drier than normal last month and only the southern seven counties were wetter than normal (Figure 4).

Overall, the preliminary statewide average total January precipitation was 1.25 inches, 1.06 inches below the 1991-2020 average and tied for the 32nd driest on record statewide.

Figure 4. Maps show (left) January total precipitation and (right) precipitation departure from normal across Illinois.

Outlooks

The Climate Prediction Center outlooks, reflecting model tendencies and expert assessments, continue to lean into La Niña influence on our late winter and early spring weather across the U.S. Here in Illinois, the expectation is for near normal temperatures and above normal precipitation for both the last winter month of February and the first two months of spring (Figure 5).

Figure 5. Maps show (left) temperature and (right) precipitation outlooks for the month of February and February through April.  
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Mild October Had a Chilly End

The preliminary statewide average October temperature was 56.7 degrees, 1.9 degrees above the 1991–2020 average and tied for the 31st warmest on record going back to 1895. The preliminary statewide total October precipitation was 3.46 inches, 0.20 inches above the 1991–2020 average and the 41st wettest on record.

Data are provisional and may change slightly over time.

Mild October Temperatures with Some Extremes Thrown In

For my money, October is the best weather month of the year. The summer heat mellows out and mixes with the first real shots of chilly air. We had both summer- and winter-like weather last month, but a little more of the former than the latter. As the daily temperature departures from normal in Mt. Vernon show, most October days had above average temperatures, including a few days in the final week of the month that were 15 to 20 degrees above normal (Figure 1).

Figure 1. Daily October average temperature departures in Mt. Vernon.

October average temperatures ranged from the low 50s in northern Illinois to the low 60s in southern Illinois, between 1 and 2 degrees above normal in most places (Figure 2). Most of the state saw high temperatures in the upper 80s or low 90s in early October, including 94 in Quincy and 90 in Hoopeston. The brief taste of winter in the last few days of the month brought widespread low temperatures in the low 20s, including 21 degrees in Mt. Vernon and 23 in Bloomington.

The warm periods last month broke 31 daily high maximum temperature records and an incredible 66 daily high minimum temperature records. Aledo in Mercer County broke its all-time October high temperature records last month with a high temperature of 93 degrees on October 3. The cold end to the month broke 18 daily low maximum temperature records and 37 daily low minimum temperature records. 

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

Overall, the preliminary statewide average October temperature was 56.7 degrees, 1.9 degrees above the 1991–2020 average and tied for the 31st warmest on record going back to 1895.

Dry Start and Wet End to October

The month-end precipitation totals across the state do not tell the entire story of October precipitation. The first two-thirds of the month were somewhat to very dry across the state, as most places were 1 to 2 inches drier than normal through October 24. More active weather brought multiple rounds of rain–and some snow–to Illinois, raising month-end totals near or above the 30-year normals. As Figure 3 shows, Peoria picked up more rain in the last 7 days of October than in the first 24 days, and the month ended just slightly wetter than normal in Peoria. The dry start to the month was ideal for fall harvest, while the wetter end of the month helped improve dry conditions that prevailed in August and September.

Figure 3. Plot of October daily precipitation accumulation in Peoria (shaded area) versus the normal daily accumulation (black line).

October precipitation ranged from nearly 6 inches in northeast Illinois to less than 2.5 inches in the St. Louis Metro East. Most of the state north of Interstate 70 was 1 to 2 inches wetter than normal, while areas farther south were just slightly drier, up to 2 inches drier than normal (Figure 4).

Figure 4. Maps show (left) October total precipitation and (right) October precipitation departure from average.

Last month wasn’t an extremely wet or extremely dry month anywhere in the state; however, the wetter conditions in the northern half of the state helped reduce drought extent from 23 percent of the state on October 3 to 7 percent on October 31. Small areas of western and southern Illinois remain in moderate drought due to longer-term precipitation deficits. For example, the first 10 months of the year have had the third lowest precipitation total in Quincy with 20.17 inches, around 10 inches below average. While topsoil moisture in western Illinois has improved from the wetter end of October, deeper layer moisture and water table levels remain less than ideal because of the long-term dryness.

Overall, the preliminary statewide total October precipitation was 3.46 inches, 0.20 inches above the 1991–2020 average and the 41st wettest on record.

A Spooky, Winter-y Halloween

Like all the horror film characters who inevitably run back into the haunted house, mild October temperatures lulled all of us into a false sense of security. The intense cold, wind, and for some folks, snow on Halloween was more shocking than the sound of a revving chainsaw. Halloween nighttime temperatures dipped into the low 20s and high teens across much of the state, including 18-degree lows in Monmouth and Rochelle (Figure 5). The daytime high temperatures on Halloween were the coldest on record in several spots across the state, including at Chicago’s Midway airport (37 degrees) and Mt. Vernon (43 degrees). The low temperatures on Halloween night also set records in many places, including in Kankakee (24 degrees) and Olney (22 degrees). In fact, this year was the coldest Halloween in Olney since observations began there in 1896.

Halloween snow in northern and central Illinois is not necessarily a rarity but happens once every 4 to 6 years. Measurable snow, with totals exceeding 0.1 inches, was recorded in much of the state north of Interstate 74, with totals as high as 1.5 inches in Mundelein and 0.9 inches at O’Hare (Figure 5). For reference, the average first measurable snow comes in the third or fourth week of November for most of northern and central Illinois, so this year’s event came about two to three weeks early. It’s important to note that an early snowfall does not mean we will necessarily have a very snowy winter… but this State Climatologist can hope.

Figure 5. Maps of (left) nighttime low temperatures and (right) total snowfall on Halloween. Maps are from the Lincoln National Weather Service Office: https://www.weather.gov/ilx/illinois-daily.

Outlooks

November doesn’t get the love it deserves, because it is so often associated with cloudy, blustery weather. But November typically gives us a great mix of pleasant and not-so-pleasant weather and portends the beautiful winter season in Illinois. The latest Climate Prediction Center outlooks lean into El Niño with higher chances of below normal November precipitation. November temperature outlooks are more mixed, with equal chances of warmer and colder weather this month (Figure 6).

Figure 6. Maps of (left) temperature and (right) precipitation outlooks for November.

Meanwhile, NOAA leans even more heavily into El Niño for climatological winter (December–February) outlooks (Figure 7). The outlooks show highest chances of above normal temperatures in winter, with mostly equal chances of above or below normal precipitation.

Figure 7. Maps of (left) temperature and (right) precipitation outlooks for winter (December–February).
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October Brought Real Fall to Illinois

The preliminary statewide average October temperature was 53.1 degrees, 1.6 degrees below the 1991–2020 average and tied for the 40th coolest on record going back to 1895. The preliminary statewide average total October precipitation was 2.30 inches, 0.61 inches below the 1991–2020 average and tied for 52nd driest on record statewide.    

Data are provisional and may change slightly over time.

Mild October Temperatures

October 2021 was the fifth warmest on record in Illinois. The unusually warm and rainy weather last year put a damper on both harvest and fall festivities. October this year though did not disappoint fall lovers. October followed September’s lead and brought mostly mild temperatures across the state. As the temperature departures from Aurora in Figure 1 show, 16 of the first 21 days in October were cooler than normal, and many were 5 to 15 degrees below normal. Only the third week of the month had temperatures more than 10 degrees above normal. Average October high temperatures ranged from the low to high 60s, with lows in the 40s and low 50s. The result was very pleasant weather across the entire month, which, along with dry conditions, permitted a relatively quick harvest and plentiful opportunities to enjoy fall festivities.

Figure 1. Daily October average temperature departures in Aurora.

Cool October nights brought regular frost across the state, and an earlier than normal first fall freeze. For example, Du Quoin recorded its first fall 32-degree freeze on October 9, about 10 days earlier than the 1991–2020 average. Most places saw nighttime temperatures dip below the hard freeze mark of 28 degrees later in the month, including a 20-degree low in Monmouth and a 22-degree low in Carbondale.

October average temperatures ranged from the upper 40s in northern Illinois to the mid-50s in southern Illinois, between 1 and 4 degrees below normal (Figure 2). The warmest place in the state last month was Olmsted in Pulaski County with an average October temperature of 58.9 degrees. The coolest place in the state was Elizabeth in Jo Daviess County with an average October temperature of 49.2 degrees.

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

Daily high maximum temperature records were broken last month at 8 stations, and daily high minimum temperature records were broken at 1 station. Daily low minimum temperature records were also broken at 17 stations. Cairo tied its all-time October low minimum temperature record with a 25-degree low on October 19.

Overall, the preliminary statewide average October temperature was 53.1 degrees, 1.6 degrees below the 1991–2020 average and tied for the 40th coolest on record going back to 1895.

Continued Dryness Causes Issues

September was drier than normal in most places around the state, and the dryness persisted into the first two-thirds of October (Figure 3). Most areas picked up less than 1 inch of total precipitation between October 1 and 21, 1 to 3 inches less than normal over the time period.

The dryness in southern Illinois was part of a larger pattern for the Ohio and Lower Mississippi River basins. In fact, the entire Lower Ohio valley, from Louisville to Cairo, only picked up 0.60 inches of total rainfall on average between September 1 and October 21. The exceedingly dry conditions contributed to very low flows and navigation issues along the Ohio and Mississippi Rivers. Extremely dry soils particularly in southern Illinois also increased the risk of fire and forced multiple counties to impose burn bans for most of the month. Despite the bans, several wildfires and field fires broke out in southern and central Illinois in October, including a fire that burned at least 115 acres in Jefferson County. One benefit of the persistently dry conditions was that it aided a relatively smooth harvest. On the other hand, low flow and navigation issues along the Mississippi River from the dry weather has contributed to higher transportation costs and grain storage issues.

        Figure 3. Maps show (left) total precipitation and (right) precipitation departure from normal between October 1 and 21.      

The last week of the month brought wetter weather statewide, including a few places that picked up 3 to 4 inches in a single week. October total precipitation ranged from over 4 inches in southwest Illinois to less than 1.5 inches in far northwest Illinois (Figure 4). The Interstate 55 corridor between St. Louis and Chicago was the only part of the state near to slightly wetter than normal, whereas northwest and southern Illinois were 1 to 3 inches drier than normal last month.

Overall, the preliminary statewide average total October precipitation was 2.30 inches, 0.61 inches below the 1991–2020 average and tied for 52nd driest on record statewide.   

Figure 4. Maps show (left) October total precipitation and (right) October precipitation departure from normal

Outlooks

Climate Prediction Center outlooks for November mostly point to equal chances of warmer/cooler and wetter/drier than normal conditions (Figure 5). However, as we continue into our third consecutive La Niña cool season, outlooks are increasingly taking a very La Niña-esque appearance. Namely, much of Illinois is leaning toward wetter than normal conditions from December through February (Figure 6). A wetter winter would be beneficial in reducing the soil moisture deficits and improving streamflow as we move into spring.   

Figure 5. Maps show (left) temperature and (right) precipitation outlooks for November.
Figure 6. Climate Prediction Center (left) temperature and (right) precipitation outlooks for December through February.