A Wet and Wild January Finally Brings Winter to Illinois

The preliminary statewide average January temperature was 25.7 degrees, 1.0 degree above the 1991–2020 average and tied for the 57th coldest on record going back to 1895. The preliminary statewide average total January precipitation was 4.50 inches, 2.19 inches below the 1991–2020 average and tied for the eighth wettest on record statewide.

Data are provisional and may change slightly over time.

Big (but Fleeting) January Chill

The very mild December weather spilled over into the new year as the first 10 to 12 days of January had temperatures near to slightly above normal. Extremely cold air moved into Illinois following a series of winter storms and brought frigid weather across the state for the middle part of the month. Daily temperature departures from normal in Figure 1 showed average temperatures were 10 to 30 degrees below normal in Kankakee between January 14 and 21. Some of the more impressive actual temperature values from that week included -25 degrees in Altona and -19 degrees in Moline. Strong northerly and northwesterly winds added to the cold and pushed wind chills into the -30- to -40-degree range. Water main breaks were reported across the state, and several school districts closed for multiple days because of the cold. Numerous deaths in the state were attributed to the cold as well. Temperatures moderated in the final week of the month, providing a well-deserved break from an Arctic winter.

Figure 1. Daily January average temperature departures in Kankakee.

January temperatures ranged from the low 20s in northern Illinois to the mid-30s in southern Illinois (Figure 2). The southern half of the state was 1 to 3 degrees colder than normal last month, and, despite the extreme cold in mid-month, northern Illinois was 1 to 2 degrees warmer than normal in January. The coldest point in the state last month was Stockton in Jo Daviess County at 20.1 degrees, and the “warmest” point was Olmstead in Pulaski County at 32.7 degrees.

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

A Wet Start to 2024

Precipitation was hard to come by for much of Illinois in the last few months of 2023. Drought impacts are usually minimal in winter, but even so there were many reports of unusually dry soils and low streams and ponds at the start of the new year. While January did not completely replenish all water lost last year, it took a big bite out of drought.

January total precipitation ranged from around 2.5 inches in northwest Illinois to nearly 10 inches in far southern Illinois (Figure 3). Everywhere in Illinois was wetter than normal in January, to the tune of 1 to 4 inches, between 150% and 300% of normal monthly precipitation. The precipitation totals were especially impressive around the Ohio River. Last month was the third wettest January on record in Paducah with 9.43 inches, and the wettest since 1969. It was also the eighth wettest January on record in Champaign and Centralia, both with over 5 inches total.

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

Overall, the preliminary statewide average total January precipitation was 4.50 inches, 2.19 inches below the 1991–2020 average and tied for the eighth wettest on record statewide.

Persistent rain followed by wet, slowly melting snow was perfect for returning moisture to the ground and starting the climb out of drought. Figure 4 shows the water table depth below ground at the Water & Atmospheric Resources Monitoring (WARM) program in Belleville. The water table is the boundary between where the soil is saturated and unsaturated, and its depth is often affected by drought. The average water table depth for this time of the year in Belleville is around 3 feet, meaning that one usually only must dig down 3 feet or so to find completely saturated soil. However, Belleville came into this year with a severely depressed water table that was around 15 feet deep. The water table has begun to inch closer to the surface thanks to the precipitation in January, but as Figure 4 shows, there is much more recovery needed to get closer to average conditions.

Figure 4. The blue line shows the current water table depth (below ground) at the WARM site in Belleville. The black line is the long-term average, and the gray shading shows water table depths in most years.

Some Snow, At Least

Depending on where you are in our great state, January is either the first or second snowiest month of the year. And if you live north or west of the Illinois River, last month fit that bill quite well. For the rest of us, January just brought more cold rain. Total January snowfall ranged from less than half an inch in southern Illinois to over 25 inches in northwest Illinois; the latter area had 4 to 15 inches above normal snowfall (Figure 5).

Most of the snow in January came immediately ahead of or during the extreme cold in the middle of the month. Moline picked up more snowfall between January 8 and January 18 than in all of 2023, and last month was the second snowiest January on record in Moline, only less than 2019. January 12 was also the second snowiest day on record in Moline, with 15.4 inches; it was only less than on January 3, 1971.

The heavy snowfall in mid-January pushed the northwest corner of the state 1 to 6 inches above normal on season-to-date snowfall. Meanwhile, most of central and southern Illinois have had 2 to 8 inches below normal snowfall (Figure 5).

Figure 5. Maps show total snowfall and snowfall departure from normal for (left) January and (right) the snowfall season to date.

Outlooks

I’m not one to rely on rodents for my seasonal climate predictions. But as it turns out this year, Punxsutawney Phil and the Climate Prediction Center agree on a mild end to winter. The maps in Figure 6 show the more reliable Climate Prediction Center outlooks for (top) February and (bottom) climatological spring, March through May. Both show higher chances of above normal temperatures. February’s outlook leans a bit more into El Niño with a nod to a drier final month of winter. Meanwhile, the March–May outlook is less confident on precipitation, with equal chances of a wet and dry spring.

Figure 6. Maps show (left) temperature and (right) precipitation outlooks for the month of February and the spring season (March–May).

2023 was Much Warmer and Drier than Normal

Illinois was both warmer and drier than the 1991–2020 normal in 2023. The statewide average annual temperature was 54.8 degrees, 2.2 degrees above normal and 5th warmest on record statewide. Statewide average total precipitation in 2023 was 34.41 inches, 6.34 inches below normal and the 29th driest year on record.

2023 Temperatures

The past year was very warm in Illinois, but the largest temperature departures from normal were during the climatologically coldest months. January, February, and December 2023 were all at least 5 degrees warmer than normal, while June, July, and August were near to slightly cooler than normal (Figure 1).

Figure 1. Plot shows 2023 statewide monthly average temperature (black line) and temperature departures from the 1991–2020 normal (red and blue bars).

Figure 2 shows 2023 average temperatures and departures from normal across the state. Average temperatures ranged from the low 50s in northern Illinois to the high 50s in southern Illinois. The entire state was between 1 and 2 degrees above normal last year.

Figure 2. Maps show 2023 annual average temperature (left) and average temperature departures from the 1991–2020 normal (right).

The year 2023 was the 2nd warmest on record in St. Louis, 3rd warmest on record in Chicago and Moline, the 7th warmest in Champaign-Urbana, the 8th warmest on record in Carbondale, the 9th warmest in Rockford, the 12th warmest in Springfield, and the 14th warmest in Quincy. The warmest point in the state last year was Du Quoin with an average temperature of 60.3 degrees. The coolest point in the state was Stockton in Jo Daviess County with an average temperature of 49.3 degrees.

Last year also tied with 1931 for warmest on record in Peoria with an average temperature of 55.6 degrees. The year 1900 had a higher annual average temperature in Peoria but had almost a month’s worth of missing daily weather observations and is therefore not considered for annual records. Figure 3 shows the record of annual average temperature in Peoria going back to the 1880s. A long-term warming trend is also evident in Peoria’s temperature record. 

Figure 3. Plot shows the annual average temperature in Peoria from 1884 to 2023.

Table 1 shows the number of daily weather records broken at Illinois Cooperative Observer stations in each month of 2023.

Table 1. Table shows the number of daily local weather records in 2023 by month and variable.

August led with the highest number of daily high maximum and daily high minimum temperature records, with 63 and 105, respectively. Two stations in Illinois broke their August high maximum temperature records in 2023. McHenry set a new August high maximum temperature record with 97 degrees on August 24 and then broke it with 98 degrees on August 25. Nine stations also broke their August high minimum temperature records in 2023, including an 81-degree low in Du Quoin on August 22. Three stations set their all-time high minimum temperature records last year in August, including a 79-degree low in Peoria on August 25. The August records were set by an intense late-season heat wave across the state. Peoria set a new heat index record of 121 degrees, breaking its previous record from 1995.

Also of note was the absence of extreme cold in the 2023 winter months. No stations broke daily low maximum or low minimum temperature records in January, February, or December. In fact, no station recorded a nighttime low temperature in the single digits in December for the first time on record in Illinois. The lowest temperature Champaign-Urbana hit all year in 2023 was 5 degrees, the second highest annual minimum temperature on record there and the lowest since 1921. While all four seasons in Illinois have warmed because of human-driven climate change, winter temperatures have increased at a much faster rate than in all other seasons (Figure 4). In winter, the most extreme low temperatures have increased at a faster rate than milder temperatures, making for less frequent and intense cold weather across the state in recent decades.

Figure 4. Maps show trends in daily average temperature in degrees Fahrenheit per decade by season and county in Illinois. Trends are calculated using observations between 1900 and 2020.

Milder temperatures in March and April also resulted in dozens of low maximum and low minimum temperature records broken across the state in 2023. However, two and a half times as many high maximum or high minimum temperature records (602) were broken last year in Illinois as low maximum or low minimum temperature records (241).

There were also 566 daily total temperature records broken across Illinois in 2023. Daily temperature records broken were somewhat equally spread among months, but February and March led with 90 and 93 degrees, respectively.

2023 Precipitation

Calendar year 2023 began with wetter than normal months in January, February, and March (Figure 5). The combination of wetter spring conditions and a large snowpack that rapidly melted in the Upper Midwest led to brief flooding along the upper Mississippi River, including the fourth highest crest on record at Davenport.

Figure 5. 2023 monthly total precipitation as a departure from the 1991–2020 normal.

April, May, and June were all somewhat to very dry across the state. Dry weather and high evaporation in late April quickly dried out topsoil and–along with strong winds and farming activity–contributed to a severe dust storm on May 1 in south-central Illinois. The near zero visibility caused a 72-vehicle pileup on Interstate 55 that killed 7 and injured another 37 (https://www.weather.gov/ilx/01may2023-dust). 

The state accumulated a nearly 6-inch precipitation deficit from April and June, which plunged most of Illinois into a significant drought. The June 27 U.S. Drought Monitor showed over 90 percent of the state in at least moderate drought and nearly 60 percent of the state in at least severe drought. Pasture conditions deteriorated rapidly in the early summer with little regrowth after the first hay cutting. Mature trees in central and northern Illinois showed significant stress and many municipalities reported substantial young tree mortality across the state.

July and August brought enough rain to limit agricultural and water resource impacts from the drought. Very heavy rain in Chicago in both July and August caused widespread flooding of hundreds of homes. Berwyn, Cicero, and Garfield Park all reported over 8 inches of rain in less than a day (https://www.weather.gov/lot/2023_07_02_Flooding).

For the second consecutive year, Illinois fell back into drought in the fall as the months of September, October, and November were all drier than normal statewide. After reaching its fourth highest crest at Davenport, the Mississippi River once again dipped below low stage in St. Louis and Memphis, forcing active dredging throughout the fall.

Overall, the preliminary statewide average total precipitation in 2023 was 34.63 inches, 6.12 inches below normal and the 30th driest year on record. Much like past years, the statewide preciptiation statistics are not representative of all places in Illinois. Calendar year 2023 had close to normal precipitation in parts of northern and southern Illinois, but was somewhat to much drier than normal in parts of central Illinois.

Figure 6 shows the spatial variability of 2023 precipitation in more detail. Total precipitation last year ranged from over 50 inches in far southern Illinois to less than 25 inches across parts of western Illinois.

Figure 6. Maps show (left) total precipitation and (right) precipitation departures in 2022.

A CoCoRaHS citizen science observer in Bush in Williamson County reported 57.23 inches of precipitation in 2023, making it the wettest point in the state. Meanwhile, the long-running station in Quincy recorded just 22.79 inches of precipitation in 2023, about 60 percent of normal. In fact, last year was the 4th driest on record in Quincy. The Gem City has only had 54 inches of precipitation since Jan. 1, 2022, making for the third driest two-year period on record there after 1953-54 and 1988-89.

2023 Severe Weather

Severe weather came early and often in 2023, with all of our 102 counties affected by strong wind, hail, tornadoes, or heavy rain (Figure 7). Overall, the NOAA Storm Prediction Center reported a preliminary 135 tornadoes in Illinois in 2023, which–if confirmed–would set a new annual tornado record, breaking the 124-event record in 2006. Figure 7 shows the monthly frequency of tornadoes in 2023 compared to the 1991–2020 average frequency. The first four months of the year had well above average tornado frequency, including the largest March tornado outbreak on record in the state (https://www.weather.gov/ilx/TornadoEvent_3-31-23). The 49 tornadoes in March 2023 represent 20 percent of all March tornadoes in Illinois since 1950. Dry weather in May and June was not conducive to severe weather, but tornado frequency was above average in July and August. Only one torando was reported in the last four months of the year. It is likely the 2023 tornado total will be adjusted, but irrespective of changes, 2023 was an extremely active tornado year.

Figure 7. Plot shows tornado frequency by month in 2023 (blue bars) compared to the 1991–2020 average (red bars).

The NOAA Storm Prediction Center also had 303 hail reports and 699 severe wind reports in Illinois in 2023. Many of the wind reports came from a strong derecho that moved through the state on June 29. Some of the worst wind damage from the event was in Springfield, and many residents went without power for nearly a week: https://www.weather.gov/ilx/june29_derecho.

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 that moved over Chicago on July 2, producing 4 to 8 inches in less than a day: https://www.weather.gov/lot/2023_07_02_Flooding. The resulting flooding on the west side of the city affected thousands of residents and spurred a disaster declaration. Later in the same month, a series of storms produced extremely heavy rainfall across southern Illinois and western Kentucky: https://www.weather.gov/pah/FloodingJuly19_2023. Widespread totals of 6 to 10 inches produced dangerous flash flooding in parts of Pulaski County. The same storm broke the Kentucky state single-day precipitation total with 12.76 inches in Graves County.

Very Mild December in Illinois

The preliminary statewide average December temperature was 39.2 degrees, 7.6 degrees above the 1991–2020 average and the 3rd warmest on record going back to 1895. The preliminary statewide average total December precipitation was 2.99 inches, 0.56 inches above the 1991–2020 average and the 30th wettest on record statewide.    

Data are provisional and may change slightly over time.

Where is Winter?

For the second time in three years Illinois has experienced an extremely mild December. All but three days last month were warmer than normal in Decatur, and several days in the second and fourth weeks of the month were 10 to 20 degrees warmer than normal (Figure 1).

Figure 1. Daily December average temperature departures in Decatur.

Table 1 shows the December average temperature, departure from normal, and ranking for several locations in Illinois. Last month was the 2nd warmest December in Rockford, the 3rd warmest in Peoria, and the 4th warmest in Chicago and Moline. None of the 120+ National Weather Service stations in Illinois recorded a low temperature in the single digits last month, and many places hit the freezing mark only a handful of nights.       

Table 1. December average temperature, departure from normal, and ranking in several places in Illinois.

When taken altogether, December average temperatures ranged from the low 30s in northern Illinois to the low 40s in southern Illinois, between 6 and 10 degrees above normal (Figure 2). The warmest place in the state last month was Du Quoin with an average December temperature of 46.1 degrees. The coolest place in the state was Stockton in Jo Daviess County with an average December temperature of 33.9 degrees. It is important to note that the nighttime low temperatures last month were much higher than normal. The preliminary average December minimum temperature in Illinois is 32.2 degrees, which would be the 2nd highest on record statewide.  

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

The mild weather last month broke 20 daily high maximum temperature records and an incredible 99 daily high minimum temperature records. No daily low maximum or daily low minimum temperature records were broken last month.

Overall, the preliminary statewide average December temperature was 39.2 degrees, 7.6 degrees below the 1991–2020 average and the 3rd warmest on record going back to 1895.

Split December Precipitation Pattern

The first month of climatological winter brought a more active storm track to the Midwest than for most of fall. December total precipitation ranged from just over 4 inches in parts of northern Illinois to less than 1 inch in parts of far southern Illinois. Most of northern Illinois was around 1 inch wetter than normal, while most of the state south of Interstate 64 was 1 to 3 inches drier than normal in December (Figure 3).

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

Overall, the preliminary statewide average total December precipitation was 2.99 inches, 0.56 inches above the 1991–2020 average and 30th wettest on record statewide.   

As is often the case in milder Decembers, snowfall was hard to come by across Illinois last month. December total snowfall ranged from around 4 inches in far northwest Illinois to less than a tenth of an inch in southern Illinois, between 1 and 8 inches below normal (Figure 4).

Figure 4. Maps show (left) December snowfall totals and (right) December snowfall departures from normal.

Outlooks

Climate Prediction Center outlooks for January are a bit different than the El Niño-esque patterns we’ve seen recently. Outlooks show mostly equal chances of above and below normal temperatures and precipitation for the first month of the season (Figure 5).

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

November Puts an End to a Warmer and Drier Fall

The preliminary statewide average November temperature was 42.3 degrees, 0.1 degree above the 1991–2020 average and tied for the 46th warmest on record going back to 1895. The preliminary statewide average total November precipitation was 0.74 inches, 2.34 inches below the 1991–2020 average and the eighth driest on record statewide.

Data are provisional and may change slightly over time. The official November precipitation total may be affected by the rainfall on the evening of November 30. Depending on if this precipitation is counted as on November 30 or December 1, which varies by the station, the official November total may be higher than the preliminary.

Mild November with a Chilly End

November can be a challenging month for those yearning for summer to come back. However, as daily average temperature departures in Dixon show, the past month brought mostly mild temperatures that felt more like mid-fall than early winter (Figure 1). Several days in the second and third weeks of the month were 5 to 10 degrees warmer than normal. Black Friday brought a big temperature change on the back of a strong cold front. The last week of the month saw temperatures that that were 5 to 15 degrees below normal, including several nighttime low temperatures in the single digits.

Figure 1. Daily November average temperature departures in Dixon.

November temperatures ranged from the high 40s in northern Illinois to the high 50s in southern Illinois, around 1 degree above normal (Figure 2). Several places saw high temperatures into the 80s in early to mid-November, including 84 degrees in Lawrenceville and 82 degrees in Cahokia. Meanwhile, the last week of the month brought some extremely low temperatures, including 3 degrees in Minonk and 4 degrees in Aurora. The coldest point in the state last month was Elizabeth at 36.6 degrees, and the warmest point was Lawrenceville at 49.1 degrees.

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

Where is that November Rain?

Most of Illinois got a good shot of rain in late October and saw its first snow around Halloween. However, the state moved into a much drier weather pattern that persisted for most of November. Month-total precipitation ranged from nearly 3 inches in northeast Illinois to less than half an inch in parts of south-central Illinois. Northern Illinois was 1 to 2 inches drier than normal, and southern Illinois was 3 to 4 inches drier than normal (Figure 3). Last month was a top five driest November in several places in the state, including the second driest on record in Fairfield (Table 1).

Figure 3. Maps show (left) November total precipitation and (right) precipitation departure from normal across Illinois.


Table 1. November total precipitation and historical ranking at several locations in Illinois.

LocationNovember Total Precipitation (inches)Historical Ranking
Danville0.523rd driest
Fairfield0.602nd driest
Champaign0.645th driest
Joliet0.704th driest
Carbondale0.434th driest
Quincy0.368th driest
Chicago0.8512th driest
Centralia0.524th driest
Freeport0.718th driest

Overall, the preliminary statewide average total November precipitation was 0.74 inches, 2.34 inches below the 1991–2020 average and the eighth driest on record statewide.

Fall in Illinois

Climatological fall includes September, October, and November, and–for my money–it is the best weather season Illinois has to offer. This past season’s average temperatures ranged from the low 50s in northern Illinois to the low 60s in southern Illinois, around 1 degree above normal (Figure 4).

Figure 4. Maps show (left) average temperatures and (right) temperature departures for climatological fall.

Fall season total precipitation ranged from over 15 inches in northern Illinois to less than 4 inches in parts of southwest Illinois. The season was near 1 to 2 inches wetter than normal in northern and parts of central Illinois and was 4 to 8 inches drier than normal in southern Illinois. Last season was the driest fall on record in Chester, with a record back to the 1890s, and it was the fourth driest fall on record in Quincy and the driest since 1956. Speaking of Quincy, Gem City is well on its way to a top five driest calendar year of its 120+ year record. Drought has consequently been a constant in much of western Illinois this year, causing agriculture and water resource impacts.    

Figure 5. Maps show (left) maps of total fall season precipitation and (right) fall precipitation departures from normal.

Overall, the preliminary statewide average fall temperature was 55.7 degrees, 1.1 degrees above the 1991–2020 average and tied for the 27th warmest on record going back to 1895. The preliminary statewide average total fall precipitation was 6.87 inches, 2.82 inches below the 1991–2020 average and the 30th driest on record statewide.

Fall Snow

Snowfall before December is typical for central and northern Illinois, and, unlike post-March snowfall, is not universally despised. Most of northern Illinois saw its first measurable snowfall around Halloween, while central Illinois had to wait until the weekend after Thanksgiving to see the white stuff accumulate. Fall season snow totals ranged from a tenth to a quarter of an inch along the Interstate 72 corridor up to 5 inches between Peoria and Monmouth (Figure 6). Most of the state outside of the Peoria to Monmouth corridor is a little less than 1 inch beyond on season-to-date snowfall, thanks to milder October and November temperatures. It’s important to note that neither an early start to snowfall nor unusually high snow totals before December forewarn snowfall between December and February.

Figure 6. Maps show (left) season-to-date snowfall total and (right) snowfall departures from normal.

Outlooks

Welcome to winter! December brings in the coldest, snowiest season of the year. However, this winter also comes with a moderate-to-strong El Niño, which often moderates winter temperatures and limits snowfall. The December outlooks lead into that pattern, with the highest chances of above normal temperatures for the final month of the year (Figure 7a). Not much changes in the winter season (December–February) outlooks, with the highest chances of both warmer than normal and drier than normal conditions across the state (Figure 7b). 

Figure 7. Maps show (left) temperature and (right) precipitation outlooks for (top) the month of December and (bottom) the winter season (December–February).