Clear Lake, IL climate
Clear Lake has chilly winters and warm summers. A typical July afternoon reaches 86°, a January night drops to 19°, and about 21 inches of snow falls in a normal winter.
NOAA 1991-2020 climate normals Updated once a decadeWhat a year in Clear Lake feels like
Winter
Spring
Summer
Fall
Clear Lake weather by month
Average highs, lows, rain and snow for every month, from NOAA’s 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | Snow on ground | 30-yr range |
|---|---|---|---|---|---|---|---|
| January | 35° | 19° | 2.1" | 4.8" | 9 | 9 | 21° – 39° |
| February | 41° | 23° | 2.0" | 7.2" | 9 | 7 | 19° – 42° |
| March | 52° | 32° | 2.7" | 3.2" | 10 | 2 | 35° – 56° |
| April | 65° | 42° | 4.2" | 0 | 11 | 0 | 47° – 60° |
| May | 75° | 53° | 4.5" | 0 | 12 | 0 | 59° – 73° |
| June | 84° | 62° | 4.4" | 0 | 11 | 0 | 68° – 76° |
| July | 86° | 65° | 3.8" | 0 | 8 | 0 | 70° – 82° |
| August | 85° | 63° | 3.4" | 0 | 9 | 0 | 69° – 79° |
| September | 79° | 55° | 3.1" | 0 | 8 | 0 | 62° – 72° |
| October | 67° | 44° | 3.2" | 0 | 10 | 0 | 51° – 61° |
| November | 52° | 33° | 3.0" | 0.5" | 9 | 0 | 35° – 50° |
| December | 40° | 24° | 2.1" | 4.9" | 9 | 6 | 18° – 41° |
| Year | 63° | 43° | 38.4" | 20.6" | 113 | 25 |
“Wet days” have at least 0.01" of rain or melted snow. “Snow on ground” counts days with 1" or more. The 30-year range is the coldest and warmest that month’s average temperature got between 1991 and 2020.
Rain and snow in Clear Lake
Clear Lake gets 38 inches of rain and melted snow a year. May is the wettest month and February the driest. Rain or snow falls on about 113 days a year. Snow covers the ground about 25 days of the year.
About 187 frost-free days a year
In half of years the last 32° night comes by April 14 and the first one by October 20. That leaves about 187 frost-free days for gardens, longer than 60% of U.S. towns.
Heating and cooling a home in Clear Lake
Engineers use “degree days” to estimate how hard a furnace or air conditioner works. In Clear Lake, 81% of that work is heating and 19% is cooling, so the furnace matters far more than the air conditioner.
Degree days measure how far each day’s average temperature falls below or rises above 65°, added up over a year. Source: NOAA station normals.
Clear Lake and its neighbors
Clear Lake borders 5 towns with climate data. January nights across them vary by 0.6°. Williams has the coldest January nights (19°) and Capital the hottest July afternoons (86°). Clear Lake’s January low is 19° and its July high 86°.
Temperatures and rain come from NOAA’s 5 km grid, so each town gets its own value.
How Clear Lake compares
Compared with every U.S. town and city on TownTapestry, each counted once.
Warmer than it used to be
The last 30 years in Clear Lake averaged 0.9° warmer than the 1900s. The biggest change is in December (+2.1°). The shift is smaller than in 81% of U.S. towns.
Change by month1991–2020 average minus 1901–2000 average, at Clear Lake’s spot on NOAA’s grid
How much a month can swing
A normal is an average, and real years wander around it. December swings the most: between 1991 and 2020 its average temperature ranged from 18° to 41°. June is the most reliable, staying within 8°.
Common questions about Clear Lake’s climate
What is the coldest month in Clear Lake?
January, with a typical high of 35° and a low of 19°.
What is the hottest month in Clear Lake?
July, with a typical high of 86° and a low of 65°. About 28 days a year reach 90°.
How much snow does Clear Lake get?
About 21 inches in a normal winter, most of it in February.
When is the first frost in Clear Lake?
In half of years the first 32° night comes by October 20, and the last spring frost by April 14.
What is the rainiest month in Clear Lake?
May, with 4.5 inches of rain and melted snow. The year totals 38 inches.
Temperatures and rainfall come from NOAA’s gridded climate normals for Clear Lake itself (about a 3-mile square). Snow, frost dates and day counts come from NOAA’s weather station at Sherman, IL (6 mi, snow) and Springfield Capital Airport, IL (8 mi, frost, heat and degree days). Normals are 30-year averages, not a forecast. Source: NOAA NCEI U.S. Climate Normals, 1991–2020 and 1901–2000.