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.
Illinois was both warmer and wetter than the 1991–2020 normal in 2024. The statewide average annual temperature was 55.5 degrees, 2.9 degrees above normal and 2nd warmest on record statewide. Statewide average total precipitation in 2024 was 40.69 inches, 0.05 inches above normal and the 43rd wettest year on record.
The Second Warmest Year on Record
The past year was very warm in Illinois, but the largest temperature departures from normal were outside of the climatologically warmest time of the year. February, March, and November were all at least 4 degrees warmer than normal, while July and August were near to slightly cooler than normal statewide (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).
Average temperatures in Illinois last year ranged from the low 50s in northern Illinois to the low 60s in southern Illinois, between 1 and 6 degrees above normal (Figure 2). The year 2024 was the warmest year on record in Chicago, Peoria, St. Louis, and Paducah, and it was a top 5 warmest year on record in the Quad Cities, Champaign-Urbana, Quincy, and Carbondale, among other places. The warmest point in the state last year was Dixon Springs in Pope County with an average temperature of 60.2 degrees. The coolest point in the state was Stockton in Jo Daviess County with an average temperature of 50.2 degrees.
Figure 2. Maps show 2024 annual average temperature (left) and average temperature departures from the 1991–2020 normal (right).
Last year was the warmest on record in Chicago, which stretches back to the 1870s. The weather station of record for the city of Chicago is currently at O’Hare airport; however, the station’s location has changed multiple times since the 1870s. For the first half of the record, the station was much closer to Lake Michigan, including in the Roanoke Building between 1873 and 1887 and Rosenwald Hall at the University of Chicago between 1926 and 1942. The Chicago National Weather Service office has a complete weather history for Chicago and Rockford: https://www.weather.gov/lot/observation_history.
Despite the likely moderating effect of the lake on temperatures in the early part of Chicago’s record, 2024 was still the warmest year since Ulysses Grant was president. Figure 3 shows the record of annual average temperature in Chicago, illustrating a long-term warming trend the city has experienced over the past 150 years.
Figure 3. Plot shows the annual average temperature in Chicago from 1873 to 2024.
Table 1 shows the number of daily weather records broken at Illinois Cooperative Observer stations in each month of 2024.
Our very mild February led with the highest number of daily high maximum temperature records, with 222 statewide. Meanwhile, the final three months of the year led with the most high minimum temperature records with 101, 67, and 64, respectively. The fleeting but intense cold air outbreak in mid-January in 2024 broke 73 low maximum temperature records and 28 low minimum temperature records. Multiple months had at least 100 daily high precipitation records broken last month, including January, April, July, and November.
Table 1. Table shows the number of daily local weather records in 2023 by month and variable.
2024 Precipitation
Calendar year 2024 had quite variable precipitation, with five months of wetter than normal conditions (January, April, July, November, December) and seven months that were drier than normal (Figure 4).
Figure 4. 2024 monthly total precipitation as a departure from the 1991–2020 normal.
Illinois experienced the 2nd driest February on record statewide, with only 0.48 inches of statewide average February precipitation, about 1.5 inches below normal. A wetter than normal April and May helped refill soils ahead of the growing season, but also delayed crop planting and critical fieldwork in many parts of the state.
For the third consecutive year Illinois fell back into drought in the fall as the months of September and October were 1 to 3 inches drier than normal across the state. Total precipitation in September and October statewide was only 3.48 inches, about 60% of normal and the 12th driest 2-month period on record. Once again, the region’s largest rivers approached low stage, including along the Illinois, Mississippi, and Ohio Rivers, causing some moderate challenges to shipping. November and December were both wetter than normal to end the year.
Figure 5 shows the spatial variability of 2024 precipitation in more detail. Total precipitation last year ranged from over 60 inches in far southern Illinois and the St. Louis Metro East area to less than 35 inches in parts of northern and north-central Illinois. Areas along the Wisconsin and Iowa borders were 2 to 6 inches wetter than normal last year, and areas around St. Louis and along the Interstate 70 corridor were 6 to 12 inches wetter than normal.
Figure 5. Maps show (left) total precipitation and (right) precipitation departures in 2024.
A CoCoRaHS citizen science observer in Metropolis in Massac County had 62.92 inches of precipitation in 2024, making the birth of Superman the wettest point in the state. Meanwhile, another CoCoRaHS observer in El Paso in Woodford County had only 28.22 inches of precipitation in 2024.
Overall, statewide average total precipitation in 2024 was 40.69 inches, 0.05 inches above normal and the 43rd wettest year on record.
2024 Severe Weather
Severe weather came early and often in 2024, with all of our 102 counties affected by strong wind, hail, tornadoes, or heavy rain (Figure 6). Overall, the NOAA Storm Prediction Center reported a preliminary 142 tornadoes in Illinois in 2024, which would set a new annual tornado record, breaking the 124 event record in 2006, and follows the very active tornado year of 2023 with 121 tornadoes. Figure 6 shows the monthly frequency of tornadoes in 2024 compared to the 1994-2023 average frequency. February through May had above average tornado frequency, and then came a record-breaking July. The 7th month of the year ended with 45 tornadoes in the state, including a massive tornado outbreak in the Chicagoland area on July 15th. In total, the derecho on that evening brought 32 confirmed tornadoes, including several that made it into the Chicago city limits: https://www.weather.gov/lot/2024_07_15_Derecho.
Only one tornado was reported in the last four months of the year. It is likely the 2024 tornado total will be adjusted, but irrespective of changes, 2024 was an extremely active tornado year and very likely the most active tornado year on record in Illinois
Figure 6. Plot shows tornado frequency by month in 2024 (blue bars) compared to the 1994-2023 average (red bars).
The NOAA Storm Prediction Center also had 216 severe hail reports and 716 severe wind reports in Illinois in 2024. Many of the wind reports came from a strong derecho that moved through the state on June 29. Over one-third of all severe wind reports came on July 15th, including 100+ mph wind reports in Marshall County and Ogle County.
2024 Snowfall
Snow was hard to come by in 2024. Figure 7 shows snowfall departures from normal between January and May, September and December, and for the 2024 year as a whole. Most places in the state had between 5 and 20 inches below normal snowfall last year. Overall, the statewide average total snowfall was just under 12 inches in 2024, below the long term average of 19 inches (Figure 7).
Figure 7. Maps of snowfall departures from normal across Illinois and a plot of statewide average total snowfall in Illinois between 1904 and 2024. The maps show departures from (left) January through May, (middle) September through December, and (right) the entire year of 2024.
The preliminary statewide average December temperature was 33.4 degrees, 1.8 degrees below the 1991–2020 average and tied for 36th warmest on record going back to 1895. The preliminary statewide average total December precipitation was 2.90 inches, 0.47 inches above the 1991–2020 average and tied for 31st wettest on record statewide.
Data are provisional and may change slightly over time.
Roller Coaster Temperatures
Day to day temperature variability in Illinois is highest in climatological winter, and December followed suit with regular dips and jumps in daily temperature, as shown in Figure 1 from Aurora. Daily average temperatures were 10 to 20 degrees below normal in the first week of the month, were 15 to 25 degrees above normal in the final week of the month, and jumped around in between (Figure 1).
Figure 1. Daily December average temperature departures in Aurora.
When taken altogether, December average temperatures ranged from high 20s in northern Illinois to the low 40s in southern Illinois, between 1 and 5 degrees above normal (Figure 2). The warmest place in the state last month was Olmstead in Pulaski County with an average December temperature of 41.4 degrees. The coolest place in the state was Stockton in Jo Daviess County with an average December temperature of 26.6 degrees.
Figure 2. Maps of (left) December average temperature and (right) December average temperature departures from normal.
The milder days last month broke 3 daily high maximum temperature records and 54 daily high minimum temperature records. Meanwhile the cooler days in December broke 23 daily low maximum temperature records and 6 daily low minimum temperature records in Illinois.
Overall, the preliminary statewide average December temperature was 33.4 degrees, 1.8 degrees below the 1991–2020 average and tied for 36th warmest on record going back to 1895.
Wetter December with Some Snow, I Guess
December wasn’t a washout anywhere but brought enough precipitation to continue improving water conditions from peak fall drought. December total precipitation ranged from over 6 inches in far southern Illinois to around 1.5 inches in northern Illinois. Most areas of the state south of Interstate 64 were 1 to 3 inches wetter than normal last month, while parts of northern Illinois were around 1 inch drier than normal (Figure 3).
Figure 3. Maps show (left) December total precipitation and (right) December precipitation departure from normal
The wettest part of the state was, again, Olmstead in Pulaski County, which picked up just over 10 inches in the final month of the year. The driest place in the state in December was Freeport, with only 0.89 inches for the month. Overall, the preliminary statewide average total December precipitation was 2.90 inches, 0.47 inches above the 1991–2020 average and tied for 31st wettest on record statewide.
As is often the case in milder Decembers, snowfall was a little harder to come by across Illinois last month. December total snowfall ranged from around 5 inches in far northern Illinois to less than a tenth of an inch in far southern Illinois, between 1 and 6 inches below normal (Figure 4). Snowfall so far this season has also been below normal across Illinois, to the tune of 1 to 10 inches.
Figure 4. Maps show (left) December snowfall totals, (middle) December snowfall departures from normal, and (right) season-to-date snowfall departures from normal.
Outlooks
Climate Prediction Center outlooks for January show an extension of colder than normal conditions from the northern Plains into much of the Midwest and Southeast US. January Outlooks show mostly equal chances of above and below normal precipitation for the first month of 2025 (Figure 5).
Figure 5. Maps show (left) temperature and (right) precipitation outlooks for January.
Meanwhile, 3-month outlooks for January through March show equal chances of warmer and cooler than normal conditions but paint a decidedly wetter than normal pattern across Illinois (Figure 6).
Figure 6. Maps show (left) temperature and (right) precipitation outlooks for January through March.
The preliminary statewide average November temperature was 46.6 degrees, 4.4 degrees above the 1991-2020 average and tied for the 10th warmest on record going back to 1895. The preliminary statewide average total November precipitation was 4.15 inches, 1.07 above the 1991-2020 average and the 20th wettest on record statewide.
Data are provisional and may change slightly over time.
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 Jacksonville show, the past month brought mostly mild temperatures that felt more like early fall than early winter (Figure 1). Several days in the first and third weeks of the month were 10 to 20 degrees warmer than normal. Thanksgiving week brought a big temperature change on the back of a strong cold front. The last few days of the month saw temperatures that that were 5 to 15 degrees below normal, including several nighttime low temperatures in the teens.
Figure 1. Daily November average temperature departures in Jacksonville.
November temperatures ranged from the low 40s in northern Illinois to the mid-50s in southern Illinois, around 2 to 7 degrees above normal (Figure 2). Several places saw high temperatures into the high 70s in early to mid-November, including 79 degrees in Decatur and Marseilles. Meanwhile, the last week of the month brought some very low temperatures, including 7 degrees in Stockton and 9 degrees in DeKalb. The coldest point in the state last month was Stockton at 41.2 degrees, and the warmest point was Du Quoin at 53.3 degrees.
Figure 2. Maps of (left) November average temperature and (right) November average temperature departures from normal.
Much November Rain for Which to Be Thankful
September and October were both very dry months across Illinois, outside of the few places that saw rain from the remnants of hurricane Helene. November flipped that script and brought quite a bit of rain across much of the state. November totals ranged from over 8 inches in the St. Louis Metro East area to around 3 inches in north-central Illinois. Parts of southwest and central Illinois were 5 to 8 inches wetter than normal last month, while much of far southern Illinois was 1 to 2 inches drier than normal (Figure 3). Some of the more impressive November totals include 9.97 inches in Granite City and 8.38 inches in Cahokia Heights. Meanwhile, Moline and Rockford only picked up around 2 inches total for the month. Last month was the wettest November on record in Edwardsville with 9.97 inches, and it was the first November since 1946 with over 9 inches of rain in Edwardsville.
Figure 3. Maps show (left) November total precipitation and (right) precipitation departure from normal across Illinois.
Overall, the preliminary statewide average total November precipitation was 4.15 inches, 1.07 above below the 1991-2020 average and the 20th wettest on record statewide.
Some Snow, At Least
Snowfall in November is not a rare occurrence, but certainly is not a mainstay in Illinois. This year, the northeast corner of the state was the big “winner” for pre-Thanksgiving snowfall, with lake-enhanced snow contributing to widespread 1.5 to 3 inch totals across the Chicagoland area last month. The Interstate 64 corridor also picked up between a quarter and half an inch of snow in the final week of November (Figure 4). Otherwise, the three months comprising climatological fall (September through November) were snow free. Fall snowfall deficits ranged from near 3 inches below normal in northwest Illinois to less than half an inch below normal in the St. Louis Metro East area (Figure 4).
Figure 4. Maps show (left) November total snowfall and (right) snowfall departure from normal for climatological fall across Illinois.
A Mild 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 mid-50s in northern Illinois to the low 60s in southern Illinois, between 2 and 5 degrees above normal (Figure 5). It was a top 10 warmest fall on record in most parts of the state, including the third warmest fall on record in Chicago, the fourth warmest on record in Peoria, and the fifth warmest on record in Champaign-Urbana. Champaign had only nine nights with minimum temperatures below freezing, which was the fewest since 1973 and the fourth fewest on record.
Overall, the preliminary statewide average temperature in fall was 57.9 degrees, 3.3 degrees above the 1991-2020 normal and the fourth warmest fall on record in Illinois.
Figure 5. Maps show (left) average temperatures and (right) temperature departures for climatological fall.
Fall season total precipitation ranged from over 15 inches in southwest Illinois to less than 4 inches in parts of north-central Illinois. Only the southwest part of the state was wetter than normal, while the rest of the state was 1 to 6 inches drier than normal this fall (Figure 6). It was a top 10 driest fall on record in Freeport (4.47 inches), Moline (3.77 inches), and Galesburg (4.52 inches).
Overall, the preliminary statewide fall total precipitation was 7.88 inches, 1.81 inches below the 1991-2020 normal and the 48th driest fall on record in Illinois. It was also the fifth consecutive drier-than-normal fall in Illinois.
Figure 6. Maps show (left) maps of total fall season precipitation and (right) fall precipitation departures from normal.
Outlooks
Welcome to winter! December brings in the coldest, snowiest season of the year. Climate Prediction Center outlooks for the month of December don’t show any strong signals for Illinois, with equal chances of a warmer, colder, drier, and wetter than normal end to 2024 (Figure 7a). Outlooks for climatological winter (December through February) are a bit more telling, with better chances of wetter than normal winter weather (Figure 7b).