February 2025 Overview
February was another cold, dry month for Illinois.
Temperatures averaged 29.4°F, 1.7° below the 1991-2020 normal for February and the 68th coldest on record (Figure 1).
Precipitation statewide in February was 1.10 inches, 1.01 inches below the long-term statewide average and the 24th driest February on record (Figure 1).
Sufficient data was not available to estimate an aggregate mean streamflow condition statewide for February.
Mean provisional streamflow data was sufficiently limited, due to winter conditions, to preclude estimating an aggregate mean streamflow condition statewide for February. Available hydrograph data suggests flow conditions were below normal to much below normal in many areas of central Illinois.
Water surface levels at the end of February were below the full pool or target level at 7 of 16 reporting reservoirs. At the end of February, Lake Shelbyville was 0.7 feet above the March 1 target level, Carlyle Lake level was 0.5 feet above the March 1 target level, and Rend Lake was 4.4 feet above the spillway level.
Lake Michigan’s mean level was below its long-term mean for the month.
Shallow groundwater levels were 1.23 feet below the long-term average at the end of February. Levels averaged 0.24 feet below January and 0.59 feet below last year (Figure 1).
Weather/Climate Information (Trent Ford)
The following description of temperatures, precipitation, severe weather, and drought comes from data compiled by networks that report to the National Oceanic and Atmospheric Administration (NOAA). These data are provisional and may change slightly over time.
February in Illinois was colder and much drier than average statewide.
Temperatures averaged 29.4°F, 1.7° below the 1991-2020 normal for February and the 68th coldest on record (Table 1a, Figure 2). February average temperatures ranged from the high 30s in southern Illinois to the low 20s in northern Illinois, between 1 and 6 degrees below normal (Figure 2). During the peak of extreme cold in mid-February, several stations saw nighttime temperatures that were well below zero, including -15 degrees in McHenry and -12 in Freeport. The warmest place in the state last month was Crab Orchard in Williamson County with an average of 38 degrees, and the coldest place in the state was Mount Carroll in Carroll County with an average temperature of 19.9 degrees.
The milder weather in the first and last weeks of the month broke 24 daily high maximum temperature records and 15 daily high minimum temperature records. Meanwhile, the extreme cold in mid-February broke 53 daily low maximum temperature records and 32 daily low minimum temperature records. While last month was cold, it was not close to a top 20 coldest February on record anywhere in Illinois.
Precipitation statewide in February was 1.10 inches, 1.01 inches below the long-term statewide average and the 24th driest February on record (Table 1a). Total February precipitation ranged from less than a quarter of an inch in parts of far western Illinois to just over 7 inches in far southern Illinois (Figure 3). Most of the state north of Interstate 64 was 1 to 3 inches drier than normal last month, while most of southern Illinois was 1 to 3 inches wetter than normal. Last month was the 4th driest February in Normal (0.21 inches), Quincy (0.10 inches), and Galesburg (0.17 inches), the 7th driest in Peoria (0.40 inches). Combined with a very dry January in central and northern Illinois, 2025 to date has been the driest start to any year on record in Bloomington-Normal and the 2nd driest start on record in Champaign-Urbana.
Snow: February total snowfall ranged from less than 2 inches in east-central Illinois to over 12 inches in far northwest Illinois. Most of the state south of Interstate 70 had 1 to 4 inches above normal snowfall last month, while the rest of the state racked up snowfall deficits of 1 to 5 inches.
Winter: Climatological winter runs from December through February and is the coldest season of the year in Illinois. Midwest winters have warmed at a much faster rate than the other three seasons over the past 100+ years because of human-caused climate change. Consequently, many of the past decade’s winter seasons have been very mild. The winter of 2024-25 also began with mild weather, with December temperatures that were 1 to 6 degrees warmer than normal. However, much colder weather throughout January and most of February outweighed the mild December, resulting in winter season temperatures that were between 1 and 5 degrees below normal for most of Illinois. The Quad Cities region was the only part of the state that experienced a warmer than normal winter, while much of the St. Louis Metro East area had a winter that was nearly 5 degrees colder than normal.
Overall, the statewide average winter temperature was 28.2 degrees, 0.9 degrees below normal and the 63rd coldest winter on record (Table 1b).
This winter season brought strong precipitation gradients across the state, with totals ranging from less than 2.5 inches in far northwest Illinois to over 15 inches in far southern Illinois. Most of the northern two-thirds of the state were 1 to 5 inches drier than normal last season, while southern Illinois was 1 to 6 inches wetter than normal in winter.
Overall, the winter of 2024-25 statewide total precipitation was 4.77 inches, 2.20 inches below normal and the 24th driest winter on record (Table 1b). It was the driest winter statewide in Illinois since 2017 and was a top 10 driest winter on record in Moultrie, Sangamon, Logan, and Morgan Counties.
Illinois Climate Network (ICN) (Jennie Atkins)
The Illinois Climate Network (ICN) consists of 19 stations across the state which collects hourly weather and soil information.
Winds averaged 7.8 mph, 0.1 mph higher than January but 0.5 mph lower than the network’s long-term February average. The windiest station was ICN Bondville (Champaign County) with an average of 11.7 mph. The highest recorded wind gust was 45.6 mph, measured at ICN Stelle (Ford County) on February 26.
Temperatures were 6° higher than January, averaging 30° for February. Station highs were in the 50s, 60s, and 70s while lows ranged from the single digits for the negative teens. The highest temperature was 75°, recorded at ICN Belleville on February 28. The lowest was -13°, measured at ICN Freeport (Stephenson County) on February 18.
Soil temperatures averaged in the mid-30s at all depths. Under bare soils, temperatures ranged from 14 to 63° at 2 inches and 22 to 55° at 4 inches. Temperatures under sod ranged from 25 to 50° at 4 inches and 28 to 47° at 8 inches.
Precipitation was 1.37 inches, 0.36 inches lower than January and 0.82 inches lower than the long-term average. The majority of this fell in southern Illinois. All northern and central stations recorded less than 1 inch for the month. However, ICN Dixon Springs (Pope County) measured 5.92 inches, the month’s highest again for February.
Surface Water Information (Bill Saylor)
Provisional monthly mean flows for this month for 26 streamgaging stations located throughout Illinois are shown in Table 2, compared to statistics of past record of monthly mean flows at those stations for the same month. Both recent and long-term data were retrieved from USGS online data services following the end of the month. Years of record values in Table 2 represent the number of past monthly values included in the Table 2 statistics; at some stations, the available record may not be continuous. Additional source data may be available from USGS.
The statewide percent of historical mean flow and percent of historical median flow were calculated by dividing the sum of the average flows this month at stations in Table 2 by the sum of the historical mean and median flows calculated for the month, respectively, at the same stations. This method is intended to weigh individual observations proportionately in the aggregate comparison. (The Illinois River and Rock River stations were excluded from the statewide calculation because other rivers listed in Table 2 contribute to their flow.)
In February, streamflow data was not available for extended periods at several gaging stations, due to winter conditions or equipment outages. Sufficient data was not available to estimate an aggregate mean streamflow condition statewide for February. Available hydrograph data suggests flow conditions were below normal to much below normal in many areas of central Illinois. Flow conditions in southernmost Illinois were above normal.
Water-Supply Lakes and Major Reservoirs. Table 3 lists selected reservoirs in Illinois, their normal pool or target water surface elevation, and data related to observed variations in water surface elevations. Reservoir levels were obtained from a network of cooperating reservoir operators who report water levels each month. Current reservoir levels reported in Table 3 are representative of the end of the reported month and are presented as the difference in feet from seasonal target level or from full pool, as applies. Years of record represent the number of past reports for the same month used to calculate the average of the month-end values presented in Table 3. For some reservoirs, this average does not include additional period of record prior to a substantial change in reservoir operation. Most reservoirs in Table 3 serve as public water supplies, with the exceptions noted in the last column.
Compared to end-of-January water levels at 16 reservoirs for which levels were reported last month and this month, reported end-of-February water levels were lower at 10 reservoirs, higher at 3 reservoirs, and about the same as at the end of January at 3 reservoirs. For the 16 reservoirs with measurements reported for the end of February, water levels were below normal target pool or spillway level at 7 reservoirs, above normal target pool or spillway level at 6 reservoirs, and at about the target level or spillway level at 3 reservoirs.
Major Reservoirs. Compared to water levels at the end of January, at the end of February the water level at Rend Lake was 1.0 foot higher, Lake Shelbyville was 1.7 feet lower, and Carlyle Lake was at about the same level as at the end of January. At the end of February, Lake Shelbyville was 0.7 feet above the March 1 target level, Carlyle Lake level was 0.5 feet above the March 1 target level, and Rend Lake was 4.4 feet above the spillway level.
Great Lakes. Current month mean and end-of-month values are provisional and are relative to International Great Lakes Datum 1985. The February 2025 mean level for Lake Michigan was 577.8 feet. The monthly mean level one year ago (February 2024) was 578.7 feet. The long-term average lake level for February is 578.4 feet, based on 1918-2023 data. In this period of record, the lowest mean level for Lake Michigan for February occurred in 1964 at 576.1 feet, and the highest mean level for February occurred in 2020 at 581.5 feet. The month-end level of Lake Michigan was 577.8 feet. All values are provided by the U.S. Army Corps of Engineers Detroit District.
Groundwater Information (Jennie Atkins)
Water tables were 0.24’ lower at the end of February. Seventeen of twenty-four stations showed decreases during the month. However, the changes were small, less than one foot. The largest decrease was 0.84’ at the Fairfield well (Wayne County) and the largest increase was 0.49’ at the Rend Lake well (Jefferson County).
Greater differences were seen in comparisons to February 2024. Thirteen wells were lower with twelve down by more than one foot. The Good Hope well (McDonough County) was 6.16’ lower than last year.
However, significant increases were seen at several wells. Most notably, the Belleville well (St Clair County) ended the month 11.40’ above 2024 and 1.85’ above the well’s long-term average.
Wells averaged 0.59’ below February 2024, 1.22’ below the 15-year average, and 1.23’ below the long-term record (Table 4).
Data sources for the IWCS include the following:
CPC - Climate Prediction Center, https://www.cpc.ncep.noaa.gov/index.php
ISWS - Illinois State Water Survey, https://www.isws.illinois.edu
MRCC - Midwestern Regional Climate Center, https://mrcc.purdue.edu/
NCEI - National Centers for Environmental Information, https://www.ncei.noaa.gov
NWS - National Weather Service, https://www.nws.noaa.gov
SPC - Storm Prediction Center, https://www.spc.noaa.gov
USACE - U.S. Army Corps of Engineers, https://www.lre.usace.army.mil
USDM - U.S. Drought Monitor, https://droughtmonitor.unl.edu
USGS - U.S. Geological Survey, https://waterdata.usgs.gov/il/nwis
WARM - Water and Atmospheric Resources Monitoring Program, https://warm.isws.illinois.edu/warm/
