January 2024 Overview
January temperatures and precipitation were above the long-term average in Illinois. Mean streamflow statewide was estimated to be above the median for the month. Shallow groundwater levels were above the long-term depths.
Air temperatures averaged 26.5 degrees F, 0.2 degrees below the 1991–2020 normal for January (Figure 1). January temperatures ranged from the low 20s in northern Illinois to the mid-30s in southern Illinois.
Precipitation statewide in January was 4.16 inches, 1.85 inches above the long-term statewide average (Figure 1). January total precipitation ranged from around 2.5 inches in northwest Illinois to nearly 10 inches in far southern Illinois.
Mean provisional streamflow aggregated statewide was estimated to be above the long-term median flow for January (Figure 1). Statistics of monthly mean provisional streamflow were not available for January 2024 due to frozen conditions significantly limiting data reliability. Monthly mean discharge values in January were estimated to range generally from normal to above normal for the month.
Water surface levels at the end of January were below the full pool or target level at 4 of 20 reporting reservoirs. At the end of January, Lake Shelbyville was 10.8 feet above the seasonal target level, Carlyle Lake was 5.5 feet above the seasonal target level, and Rend Lake was 0.7 feet above the spillway level. Lake Michigan’s mean level was above its long-term mean for the month.
Shallow groundwater levels were 0.16 feet above the long-term average at the end of January (Figure 1). Levels averaged 4.33 feet above those in December and 0.88 feet above last year’s levels.
Weather/Climate Information
The following description of temperatures, precipitation, and snow 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.
January in Illinois was slightly cooler and much wetter than normal.
Temperatures averaged 26.5 degrees F, 0.2 degrees below the 1991–2020 normal for January (Table 1, Figure 2). Last month was the 59th coldest January on record statewide.
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. 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.
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.
Precipitation statewide in January was 4.16 inches, 1.85 inches above the long-term statewide average (Table 1). Last month was the 14th wettest January on record statewide. 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. Although 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 percent 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.
Snow: 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.
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.
Illinois Climate Network (ICN) (Jennie Atkins)
The Illinois Climate Network (ICN) consists of 19 stations across the state that collect hourly weather and soil information.
Winds averaged 7.5 mph in January, 0.6 mph lower than in December but 0.8 mph lower than the network’s long-term average. ICN Stelle (Ford County) had the windiest month with an average of 11.7 mph. The highest recorded wind gust was 45.4 mph, recorded at ICN Bondville (Champaign County) on January 12.
Temperatures averaged 27 degrees for the month, 12 degrees lower than in December and 1 degree cooler than the long-term average. However, behind the average were cooler and warmer than normal temperatures. All stations but one had monthly lows in the negatives. ICN Monmouth (Warren County) recorded -22 degrees on January 14, the network’s lowest for the month. Highs were in the 40s and 50s for most stations. The month’s highest was 58 degrees, measured at ICN Dixon Springs (Pope County) on January 24.
Soil temperatures fell 6 to 7 degrees with averages in the mid-30s. Under bare soils, temperatures at 2 inches ranged from 12 to 56 degrees and from 18 to 50 degrees at 4 inches. Temperatures under sod ranged from 24° to 47° at 4 inches and 27 to 47 degrees at 8 inches.
Precipitation increased at most ICN stations in January with a network average of 4.87 inches, 1.89 inches higher than in December and 2.25 inches higher than the long-term average. The highest totals were at the southern stations which saw heavy rains. ICN Dixon Springs (Pope County) recorded 9.35 inches, the month’s highest. Lower totals were measured at the northern stations where precipitation was mainly snow.
Soil moisture data will be provided again in Spring 2024.
Surface Water Information (Bill Saylor)
Provisional monthly mean flows The statewide percent of historical mean flow and percent of historical median flow are calculated by dividing the sum of the average flows this month at stream gaging stations by the sum of the historical mean and median flows calculated for the month, respectively, at the same stations. This method is intended to weight individual observations proportionately in the aggregate comparison. (The Illinois River and Rock River stations are excluded from the statewide calculation because other rivers contribute to their flow.)
Due to frozen conditions during the month significantly limiting reliability of streamflow data, aggregate statistics of monthly mean provisional streamflow statewide were not available for January 2024. The limited amount of reliable data posted suggests that monthly mean streamflow conditions in Illinois were generally normal to above normal for January.
Water-Supply Lakes and Major Reservoirs. Table 2 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 are obtained from a network of cooperating reservoir operators who report water levels each month. Current reservoir levels reported in Table 23 are representative of the end of the reported month and are presented as the difference in feet from the 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 23. For some reservoirs, this average does not include an additional period of record prior to a substantial change in reservoir operation. Most reservoirs in Table 23 serve as public water supplies, with the exceptions noted in the last column.
Compared to end-of-December water levels at 19 reservoirs for which levels were reported last month and this month, reported end-of-January water levels were lower at 2 reservoirs, higher at 15 reservoirs, and about the same as at the end of December at 2 reservoirs. For the 20 reservoirs with measurements reported for the end of January, water levels were below the normal target pool or spillway level at 4 reservoirs, above normal target pool or spillway level at 12 reservoirs, and at about the target level or spillway level at 4 reservoirs. Kinkaid Lake level had been drawn down intentionally for annual maintenance.
Major Reservoirs. Compared to water levels at the end of December, at the end of January the water level at Lake Shelbyville was 5.4 feet higher, Carlyle Lake was 3.4 feet higher, and Rend Lake was 2.2 feet higher. At the end of January, Lake Shelbyville was 10.8 feet above the seasonal target level, Carlyle Lake was 5.5 feet above the seasonal target level, and Rend Lake was 0.7 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 January 2024 mean level for Lake Michigan was 578.8 feet. The monthly mean level one year ago (January 2023) was 578.9 feet. The long-term average lake level for January is 578.5 feet, based on 1918–2022 data. In this period of record, the lowest mean level for Lake Michigan for January occurred in 2013 at 576.0 feet, and the highest mean level for January occurred in 2020 at 581.6 feet. The month-end level of Lake Michigan was 578.8 feet. All values are provided by the U.S. Army Corps of Engineers Detroit District.
Groundwater Information (Jennie Atkins)
Water tables rose again at wells across the state in January, ending the month 4.33 feet above the December average (Table 3).
Levels increased at 23 of the 24 monitored wells with most wells rising more than 2 feet. The ICN Bondville well (Champaign County) was 10.44 feet higher at the end of January, the month’s highest increase.
Smaller but significant improvements were seen in comparison to the previous year and the 15-year average. Fourteen wells ended the month higher than in January 2023, and 13 wells had levels higher than their 15-year average. Most notably was the Monmouth well (Warren County) in western Illinois, which rose over 6 feet in January to end the month 7.95 feet higher than last year and 4.06 feet higher than its 15-year average.
Wells averaged 0.88 feet above those in January 2023, 0.06 feet below the 15-year average, and 0.16 feet above the long-term record.
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://www.isws.illinois.edu/warm
