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The preliminary statewide average February temperature was 27.2 degrees, 3.0 degrees below the 1991–2020 average and tied for 42^nd coldest on record going back to 1895. The preliminary statewide average total February precipitation was 3.41 inches, 1.48 inches above the 1991–2020 average and the 9^th wettest on record statewide.    

Data are provisional and may change slightly over time

Variable, But Cold February

Climatologically, February is the second coldest month statewide after January. Much like January, February temperatures also tend to be quite variable day to day.

Figure 1 shows daily temperature departures from normal in Chicago over the course of the climatological winter (December–February). Following a very warm December–the fourth warmest on record in Chicago–temperatures since the beginning of the new year have been variable, but mainly colder than normal. About two-thirds of January and February days were colder than normal in Chicago.

February average temperatures ranged from the low 20s in northern and north-central Illinois to the high 30s in far southern Illinois, between 1 and 6 degrees below the 1991–2020 normal. Several stations saw daily high temperatures in the high 60s in mid-February, including 67 degrees in Alexander and Pope Counties. Meanwhile, stations in northern and central Illinois saw nighttime low temperatures well below 0, including -9 degrees in Knox County and -8 degrees in Woodford County.

Altogether, daily high maximum temperature records were broken at seven stations in February, and daily high minimum temperature records were broken at five stations. Despite the persistently below normal temperatures last month, no daily low minimum or low maximum temperature records were broken.

Overall, the preliminary statewide average February temperature was 27.2 degrees, 3.0 degrees below the 1991–2020 average and tied for the 42^nd coldest on record going back to 1895.

Tale of Two Winters

February wrapped up a climatological winter season that, even more than other winters, cannot be summarized by seasonal averages and totals alone. As Figure 3 shows, winter started with extremely mild weather in December statewide, followed by a cold but dry January. February was really the only month that brought both winter-like temperatures and the active weather we expect from Illinois winter.

The 2021-2022 climatological winter average temperatures ranged from the low 20s in northern Illinois to the high 30s in southern Illinois, within 1 degree of normal statewide (Figure 4). Overall, the preliminary statewide average winter temperature was 29.5 degrees, 1.3 degrees above the 1991–2020 normal and tied for the 41^st warmest on record.

Wet February

After a very dry January, February brought more active weather to most of the state. Total February precipitation ranged from less than 1 inch in far northwest Illinois to over 9 inches in parts of southern Illinois. Last month was about 1 inch drier than normal in northwest Illinois, 1 to 2 inches wetter than normal in central Illinois, and 4 to 7 inches wetter than normal in southern Illinois. Two observers near Cobden in Union County measured more than 9 inches of rain in February, one of the top 20 highest February totals on record statewide. Meanwhile, several stations in northwest Illinois recorded less than three-quarters of an inch of precipitation for February, including 0.63 inches in Freeport and 0.57 inches in Stockton. It was a top 10 driest February on record in Dubuque, Iowa.

Unfortunately, February precipitation patterns reinforced a dry north-to-wet south pattern in Illinois, present since the fall. The heavy February rain and snow melt in southern Illinois has caused several spots along the Wabash and Ohio Rivers and tributaries to reach or exceed moderate flood stage. Excessively wet soils in southern Illinois also raise concerns of continued flooding risks and possible fieldwork issues as we approach the start of the growing season. Concurrently, the dry winter has not helped alleviate drought conditions across northern Illinois, as the U.S. Drought Monitor expanded or continued moderate to severe drought from Lake County to Rock Island County.

The preliminary statewide average total February precipitation was 3.41 inches, 1.48 inches above the 1991–2020 average and the 9^th wettest on record statewide.

The climatological winter total precipitation ranged from just around 3 inches in far northwest Illinois to nearly 20 inches in southern Illinois. Winter was between 2 and 3 inches drier than normal in western and northwest Illinois, within 1 inch of normal in central Illinois, and 5 to 7 inches wetter than normal in far southern Illinois. The preliminary statewide total winter precipitation was 7.26 inches, 0.72 inches above the 1991–2020 normal, and the 41^st wettest on record.

Finally, Some Snow!

After a very slow start to winter, much of the state finally saw considerable snowfall in February. A series of winter storms in early to mid-February brought several rounds of moderate to heavy snowfall, with the highest totals along and around the Interstate 55 corridor from St. Louis to Chicago.

Overall, February total snowfall ranged from less than 4 inches in southern and far northwest Illinois to over 20 inches in parts of central and northeast Illinois. February snowfall was 2 to 4 inches below normal in drought-stricken northwest Illinois, within 2 inches of normal in northeast and southern Illinois, and 6 to 12 inches above normal from the St. Louis Metro East through central Illinois into the southern Chicagoland area.

Heavy February snowfall broke daily snowfall records at 53 stations in Illinois, and the 8.33 inches observed on February 3 in Jerseyville broke their all-time February daily snowfall record. Some of the most impressive single-day snowfall totals from last month include 14 inches in Woodford County on February 2, 11.8 inches in Cook County on February 2, and 10.5 inches in Vermilion County on February 3.

The heavy snowfall caused significant transportation impacts throughout February, including closures along Interstates 38, 55, 57, and 74 in central and north-central Illinois due to poor road conditions and traffic accidents. The mid-February winter storm caused a 100+ vehicle pileup on Interstate 39 north of Bloomington-Normal (Figure 7), shutting down the Interstate for several days.

The technical climatological winter season is from December through February; however, as we all know, the snowfall season can begin much earlier and end much later. A good estimate of the full winter snowfall season in Illinois is from October 1 through May 1. Figure 8 shows the winter season to date total snowfall and departures from normal. Since October 1, snowfall totals have ranged from just under 5 inches in southern Illinois to over 20 inches in northeast Illinois.

The area of the highest February snowfall from the northern edge of the St. Louis Metro East area to the southern edge of Chicagoland has been 1 to 10 inches snowier than normal since October 1, while snowfall in much of the rest of the state has been 2 to 7 inches below normal. The season total deficits are highest north of Interstate 80, with much of northern Illinois having 10 to 15 inches less snow than normal by the end of February.

March & Spring Outlooks

March is a celebratory month in many ways, but one of the most significant is the start of climatological spring. The most recent March outlooks from the Climate Prediction Center are leaning toward a warmer than normal start to spring and show strongly elevated odds of a wetter than normal March (Figure 9).

This is good news for parts of northern Illinois that have not had enough precipitation in winter to make up for drought and deficits in summer and fall. However, the news of a potentially wetter than normal start to spring is less welcome in southern Illinois. A wet start to an already typically wet season increases the risk of excessively wet soil issues and flooding in southern Illinois this spring.

The spring seasonal outlooks (March–May) are very similar to those for March, leaning toward warmer and wetter weather for most of the state.

The preliminary statewide average January temperature was 21.1 degrees, 5.6 degrees below the 1991–2020 average and the 27^th coldest on record going back to 1895. The preliminary statewide average total January precipitation was 1.17 inches, 1.14 inches below the 1991–2020 average and the 25^th driest on record.  

Data are provisional and may change slightly over time

Winter Temperatures Return

Following the second warmest December on record statewide, a return to winter-like temperatures was quite a shock to the system. Although temperatures last month were quite variable–typical of January–on average they were 3 to 8 degrees below normal.

Figure 1 shows daily temperature departures from normal at Chicago’s Midway Airport. Most January days in Chicago were colder than normal, some 15 to 20 degrees below normal in early and late January. Although last month’s temperatures were not nearly record breaking, it was the coldest January since 2014 in Chicago, Rockford, Moline, Peoria, Springfield, Quincy, and St. Louis.

January average temperatures ranged from the low teens in northern Illinois to the low 30s in southern Illinois, between 2 and 8 degrees below normal (Figure 2). High temperatures reached into the mid- to high 60s in southern Illinois last month, including 68 degrees in Pope County and 67 degrees in Alexander County. Meanwhile, nighttime low temperatures frequently dipped below zero in central and northern Illinois last month, including lows of -22 degrees in Kane County and -20 degrees in Jo Daviess and Carroll Counties.

The variable January temperatures broke 4 daily high maximum temperature records, 3 daily low maximum temperature records, and 2 daily low minimum temperature records. Overall, the preliminary statewide average January temperature was 21.1 degrees, 5.6 degrees below the 1991–2020 average and the 27^th coldest on record going back to 1895.

Dry January Extends Snow Drought

The abnormally dry pattern that has affected most of the northern two-thirds of the state since November has persisted throughout January. Total January precipitation ranged from less than a tenth of an inch in central Illinois to over 5 inches in far southern Illinois (Figure 3). Most areas north of the Highway 13 corridor were 1 to 3 inches drier than normal, while the southern seven counties were 1 to 3 inches wetter than normal.

January precipitation patterns were like those in November and December, continuing the north-south, dry-wet pattern over the past 90 days. Since November 1, areas outside of the south seven counties were 2 to 6 inches drier than normal. In fact, the period between November 1 and January 31 was the driest on record in Macomb since 1903.

Snowfall essentially requires two ingredients: (1) cold-enough temperatures to permit the snow to reach the ground and (2) enough moisture in the air to precipitate as snow. In November we had enough cold air in the region, but the air was too dry to amount to much snowfall. In December we generally had enough moisture in the air, but the persistently warm weather ensured most of the month’s precipitation was in liquid form. In January we went back to the dry, cold pattern, which resulted in below normal snowfall for most of the state.

January snowfall totals ranged from over 10 inches in parts of northern Illinois to less than half an inch in central and southern Illinois (Figure 4). Totals for the month were near to above normal in far western Illinois and the Chicagoland area, but were 1 to 8 inches below normal in central Illinois.

The snow season was mild statewide through the end of January. Snowfall totals going back to the start of October are between 5 and 15 inches below normal, with the highest deficits in northern and east-central Illinois.

With the liquid water content of snow and rainfall taken together, the preliminary statewide average total January precipitation was 1.17 inches, 1.14 inches below the 1991–2020 average and the 25^th driest on record.  

Outlooks

As I write this monthly summary on February 1, there is currently a winter storm warning for most of central Illinois and parts of northern Illinois. Forecasted snowfall totals range from 4-12 inches, with some areas in central Illinois expected to get more than a foot of snow before the end of the week. So, it’s likely our February summary will be very different from January’s, at least from a winter weather perspective.

Looking beyond the looming winter storm, the most recent February outlooks from the Climate Prediction Center show elevated odds of wetter than normal conditions statewide, with slightly higher odds of warmer than normal weather in southern Illinois (Figure 5).

The three-month outlooks for February, March, and April together show a similar pattern of warmer and wetter than normal conditions to wrap up winter and begin climatological spring. These outlooks are still guided by La Niña conditions, but other indicators do point to a wetter three-month period than the last few months.

Illinois was both warmer and wetter than the 1991–2020 normal in 2021. The statewide average annual temperature was 53.7 degrees, 1.1 degrees above normal and tied for the 10^th warmest year on record. Statewide total precipitation in 2021 was 41.06 inches, 0.31 inches above normal and the 37^th wettest year on record.

2021 Temperatures

The mild start to the 2020-2021 winter spilled over into the first month of the year. January average temperatures were nearly 3 degrees above the 1991–2020 normal. This was followed by an extremely cold February that was 10 degrees below the 1991–2020 normal and the 11^th coldest on record statewide. March was nearly 5 degrees warmer than normal, followed by April and May, which were both slightly cooler than normal. Although July was slightly cooler than normal, it was outweighed by June and August that were both nearly 2 degrees warmer than normal. September and October were 2.7 and 5.4 degrees above normal, respectively. October was the sixth warmest on record statewide and the warmest since 1971. The year ended with a slightly cooler than normal month of November and an extremely warm December that was 8 degrees above normal. The final month of 2021 was the second warmest December on record statewide.

The maps below show 2021 average temperatures and departures from normal across the state. Average temperatures ranged from the high 40s in far northern Illinois to the high 50s in the southern half of the state. Most of the state was 1 to 2 degrees warmer than the 30-year normal, whereas the southern two-thirds of the state was within 1 degree of normal, and northeast Illinois was 2 to 3 degrees warmer than normal.

The year 2021 tied with 1998 as the 4^th warmest year on record in Chicago and was the 4^th warmest year in Rockford, the 7^th warmest year in Moline, the 6^th warmest in St. Louis, and the 13^th warmest in Peoria. Statewide, 10 of the top 20 warmest years on record have occurred since 1990.

The table below shows the number of daily weather records broken at Illinois Cooperative Observer stations in each month of 2021.

December led with the most number of high daily maximum temperature records with 116, and October led with the most high daily minimum temperature records with 60. Fifteen stations in Illinois also broke the all-time December high maximum temperature records in 2021, including a 72-degree high in Galesburg on December 16.

Last year’s intense February broke 243 daily low maximum temperature records and 92 daily low minimum temperature records, the highest of all months. Over the entire year, more than twice as many low maximum temperature records were broken as low minimum temperature records. Illinois’ climate has warmed over the past 100 years, but daily minimum temperatures have increased at a larger rate than daily maximum temperatures. This disproportionate change resulted in fewer daily low minimum temperature records broken.

Daily	High Maximum Temperature	High Minimum Temperature	Low Maximum Temperature	Low Minimum Temperature	High Precipitation
January	0	1	0	0	59
February	0	0	243	92	46
March	20	18	0	0	76
April	13	41	34	21	41
May	6	24	54	44	40
June	32	21	1	12	51
July	1	1	51	3	78
August	7	36	17	4	54
September	25	6	0	0	19
October	14	60	0	0	157
November	0	0	0	2	1
December	116	59	0	0	44
Total	234	267	400	178	666

There were also 666 daily total precipitation records broken across Illinois in 2021. This included 157 daily precipitation records from a very wet October. In fact, nine stations broke the all-time October daily precipitation records, including 4.32 inches on October 24 in Rantoul in Champaign County.

2021 Precipitation

Calendar year 2021 began with a slightly wetter than normal January and slightly drier than normal February. March was more than 1 inch wetter than normal statewide, but the onset of drought in northern Illinois in spring resulted in drier than normal months in April and May. All three months of climatological summer were wetter than normal, July was nearly 1 inch wetter than normal. Fall was a roller coaster, as September was about 1 inch drier than normal, followed by the fifth wettest October on record statewide and the ninth driest November on record statewide.

In 2021, perhaps more than most years, the statewide precipitation numbers do not properly reflect the variability of precipitation between different parts of the state. Figure 4 shows the 2021 monthly precipitation departure from normal in Rockford, Springfield, and Carbondale. While only three months of 2021 were wetter than normal in Rockford and four months were wetter than normal in Carbondale, eight months in Springfield were wetter than normal. In fact, Springfield observed five months in 2021 with more than 5 inches of precipitation, only the third time in its 120+ year record (other years were 1898 and 1977).

The maps below show the spatial variability of 2021 precipitation in more detail. Total annual precipitation ranged from less than 30 inches in northern Illinois to nearly 50 inches in southern Illinois. While most of northern Illinois was 4 to 8 inches drier than normal, most of central Illinois was 4 to 12 inches wetter than normal.

One CoCoRaHS observer in Shelby County recorded 61 inches of precipitation in 2021, while several CoCoRaHS observers in Stephenson, Winnebago, Boone, McHenry, and Lake Counties observed less than 26 inches in 2021. The year 2021 was the 5^th driest year on record in Rockford with just 24.2 inches (65 percent of normal) and the 10^th driest year on record in Freeport.

Meanwhile, 2021 was also the 14^th wettest year on record in Peoria, the 13^th wettest year in Springfield, the 6^th wettest year in Bloomington, the 8^th wettest year in Danville, and the 15^th wettest year in Jacksonville.

2021 Severe Weather

Last year brought more than its fair share of severe weather across Illinois. 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 80 tornado reports, 64 hail reports, and 453 wind reports statewide in 2021.

The 80 tornado reports compare to 74 in 2020 and just 51 in 2019 and a long-term average of about 60 tornadoes per year statewide. Unfortunately, the December 10 tornado outbreak included Illinois’ first tornado-related fatalities since 2017. More information on that severe weather event is available here: https://stateclimatologist.web.illinois.edu/2021/12/16/the-december-2021-tornado-outbreak-in-illinois/.

Other noteworthy severe weather events included the June 20 EF-3 tornado in the Chicago suburbs of Naperville and Woodridge. This was the strongest tornado in the Chicago National Weather Service area since the 2017 Ottawa EF-3 event, and the strongest tornado this close to the city of Chicago since the 1991 Lemont EF-3 event. The year also brought several very heavy precipitation events across northern and central Illinois. Among these was a series of storms in late June that produced over 8 inches of rain in just 4 days in Bloomington-Normal (https://www.weather.gov/ilx/June24282021_storms), and storms that produced over 10 inches of rain in just 6 hours in Gibson City in Ford County (https://www.weather.gov/lot/2021aug12, https://atmos.illinois.edu/news/2021-09-17/story-map-gibson-city-flooding-event). 

2021 Consistent with Long-term Trends

Both temperature and precipitation have increased across the state over the past century, which define climate change in Illinois. The plot below shows the number of years in each decade between 1901 and 2020 in which the statewide average temperature and total precipitation were above and below the 1901–2020 average. Recent decades have tended to have more warmer and wetter than average years, and the most recent decade (2011–2020) had the highest incidence of both warmer than average and wetter than average years, 8th out of 10 each.

The preliminary statewide average December temperature was 39.4 degrees, 9.6 degrees above the 1991–2020 average and the second warmest on record going back to 1895. The preliminary statewide average total December precipitation was 2.70 inches, 0.02 inches above the 1991–2020 average and tied for the 40^th wettest on record.  

Data are provisional and may change slightly over time

Unusually Warm December

December is the first month of climatological winter, but the weather felt more like an extension of fall throughout most of the month.

Figure 1 shows daily temperature departures from normal in Quincy. Most December days in Quincy were between 10 and 30 degrees warmer than normal, making last month the second warmest December on record in Quincy. December was also the warmest on record in Carbondale, the third warmest on record in St. Louis, Springfield, and Peoria, the fourth warmest in Rockford and Champaign-Urbana, and the fifth warmest in Chicago.

December average temperatures ranged from the low 30s in northern Illinois to the high 40s in southern Illinois, between 6 and 12 degrees above normal (Figure 2). High temperatures regularly reached into the 70s last month in southern Illinois, including a 78-degree high in Randolph County on December 4. Carbondale recorded 74 degrees on December 25, one of the warmest Christmas Day temperatures on record in the state. Although fleeting, we did see very cold temperatures in December, including nighttime lows in the single digits across much of northern Illinois.

Overall, the preliminary statewide average December temperature was 39.4 degrees, 9.6 degrees above the 1991–2020 average and the 2^nd warmest on record going back to 1895.

Where is the Snow?

November was drier than normal virtually everywhere in the state, and that dryness persisted in December for the western half of the state. Total December precipitation ranged from around 1 inch in far western Illinois to nearly 6 inches in far southeast Illinois (Figure 3). Most of western Illinois was 0.50 to 1.5 inches drier than normal, whereas eastern and southern Illinois were near to 0.50 inches wetter than normal for the month.

Snowfall essentially requires two ingredients: (1) cold-enough temperatures to permit the snow to reach the ground and (2) enough moisture in the air to precipitate as snow. In December we generally had enough moisture in the air, but the persistently warm weather ensured most of the month’s precipitation was in liquid form. Consequently, snowfall was 1 to 8 inches below normal in December. Snow totals ranged from 4 inches in far northwest Illinois to 0 south of Interstate 72 (Figure 4).

Many places did not record their first measurable snow until the last week of the month. Chicago recorded their first measurable snowfall of the season on December 28, eight days later than the previous recorded latest first snowfall (December 20, 2012). Most places in south-central and southern Illinois did not record any measurable snowfall in December, including in Springfield. The capital city has made it to January 1 without measurable snowfall only twice in its 120-year record, in 1912 and in 2020. 

With the liquid water content of snow and rainfall taken together, the preliminary statewide average total December precipitation was 2.70 inches, 0.02 inches above the 1991–2020 average and tied for the 40^th wettest on record.  

December Severe Weather

Severe weather, including tornadoes, hail, and strong winds, tend to have the highest frequency in Illinois between April and June. However, unlike Atlantic hurricanes or extreme cold, Illinois does not have a “tornado season” because tornadoes and other severe weather can and do occur all year in the Land of Lincoln. This past month we got an awful reminder of this fact.

The exceptionally warm weather and large-scale dynamics in December made for conducive conditions for severe weather, and indeed we had more than our fair share of severe weather last month. The most noteworthy event was on the night of December 10, when severe thunderstorms moved across the southern Midwest and the mid-south, resulting in multiple very strong tornadoes in Illinois, Missouri, Arkansas, Tennessee, and Kentucky.

The tornado outbreak was responsible for dozens of fatalities across the area, including six deaths in Illinois, many injuries, and damage or destruction to thousands of homes and structures. More details on the Illinois-side of the severe weather outbreak are here: https://stateclimatologist.web.illinois.edu/2021/12/16/the-december-2021-tornado-outbreak-in-illinois/.

Overall, the NOAA Storm Prediction Center shows nine tornado reports in Illinois for December. Illinois averaged just over one December tornado per year between 1950 and 2020.

 Outlooks

After a wimpy start to climatological winter, near and longer term outlooks are indicating the potential for real winter weather in the Midwest. Meanwhile outlooks for the entire month of January show the highest odds of near to below normal temperatures and above normal precipitation, still reflecting some of the weakening La Niña pattern in the Pacific (Figure 5).