Forest Lake, IL climate
Forest Lake has chilly, snowy winters and pleasant summers. A typical July afternoon reaches 83°, a January night drops to 15°, and about 43 inches of snow falls in a normal winter.
NOAA 1991-2020 climate normals Updated once a decadeWhat a year in Forest Lake feels like
Winter
Spring
Summer
Fall
Forest 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 | 30° | 15° | 1.9" | 11.0" | 10 | 18 | 13° – 34° |
| February | 34° | 18° | 1.8" | 12.8" | 10 | 16 | 14° – 37° |
| March | 45° | 27° | 2.3" | 5.3" | 11 | 6 | 28° – 51° |
| April | 58° | 37° | 3.9" | 1.8" | 12 | 1 | 39° – 53° |
| May | 69° | 48° | 4.3" | 0 | 14 | 0 | 53° – 65° |
| June | 79° | 57° | 4.6" | 0 | 12 | 0 | 64° – 73° |
| July | 83° | 62° | 3.9" | 0 | 10 | 0 | 67° – 79° |
| August | 81° | 61° | 3.9" | 0 | 10 | 0 | 65° – 77° |
| September | 74° | 53° | 3.5" | 0 | 9 | 0 | 58° – 69° |
| October | 62° | 42° | 3.2" | 0 | 11 | 0 | 47° – 58° |
| November | 47° | 31° | 2.5" | 2.5" | 10 | 2 | 31° – 48° |
| December | 35° | 21° | 2.1" | 9.7" | 11 | 12 | 15° – 38° |
| Year | 58° | 39° | 37.7" | 43.1" | 128 | 55 |
“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 Forest Lake
Forest Lake gets 38 inches of rain and melted snow a year. June is the wettest month and February the driest. Rain or snow falls on about 128 days a year. Snow covers the ground about 55 days of the year.
About 172 frost-free days a year
In half of years the last 32° night comes by April 29 and the first one by October 20. That leaves about 172 frost-free days for gardens, shorter than 58% of U.S. towns.
Heating and cooling a home in Forest Lake
Engineers use “degree days” to estimate how hard a furnace or air conditioner works. In Forest Lake, 91% of that work is heating and 9% 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.
Forest Lake and its neighbors
Forest Lake borders 2 towns with climate data. January nights across them vary by 0.0°. Hawthorn Woods has the coldest January nights (15°) and Kildeer the hottest July afternoons (83°). Forest Lake’s January low is 15° and its July high 83°.
Temperatures and rain come from NOAA’s 5 km grid, so each town gets its own value.
How Forest 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 Forest Lake averaged 1.2° warmer than the 1900s. The biggest change is in December (+2.6°). The shift is smaller than in 51% of U.S. towns.
Change by month1991–2020 average minus 1901–2000 average, at Forest Lake’s spot on NOAA’s grid
How much a month can swing
A normal is an average, and real years wander around it. February swings the most: between 1991 and 2020 its average temperature ranged from 14° to 37°. June is the most reliable, staying within 9°.
Common questions about Forest Lake’s climate
What is the coldest month in Forest Lake?
January, with a typical high of 30° and a low of 15°.
What is the hottest month in Forest Lake?
July, with a typical high of 83° and a low of 62°. About 11 days a year reach 90°.
How much snow does Forest Lake get?
About 43 inches in a normal winter, most of it in February.
When is the first frost in Forest Lake?
In half of years the first 32° night comes by October 20, and the last spring frost by April 29.
What is the rainiest month in Forest Lake?
June, with 4.6 inches of rain and melted snow. The year totals 38 inches.
Temperatures and rainfall come from NOAA’s gridded climate normals for Forest Lake itself (about a 3-mile square). Snow, frost dates and day counts come from NOAA’s weather station at Mundelein 4 Wsw, IL (3 mi) away. Normals are 30-year averages, not a forecast. Source: NOAA NCEI U.S. Climate Normals, 1991–2020 and 1901–2000.