River Forest, IL climate
River Forest has chilly, snowy winters and warm summers. A typical July afternoon reaches 84°, a January night drops to 17°, and about 42 inches of snow falls in a normal winter.
NOAA 1991-2020 climate normals Updated once a decadeWhat a year in River Forest feels like
Winter
Spring
Summer
Fall
River Forest 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 | 32° | 17° | 2.0" | 12.6" | 11 | 17 | 16° – 36° |
| February | 36° | 20° | 1.8" | 14.5" | 10 | 18 | 16° – 39° |
| March | 47° | 29° | 2.3" | 4.1" | 12 | 6 | 31° – 53° |
| April | 59° | 39° | 3.8" | 0.8" | 12 | 1 | 41° – 55° |
| May | 70° | 49° | 4.6" | 0 | 13 | 0 | 54° – 66° |
| June | 80° | 59° | 4.3" | 0 | 13 | 0 | 65° – 74° |
| July | 84° | 65° | 3.7" | 0 | 10 | 0 | 69° – 81° |
| August | 82° | 63° | 4.0" | 0 | 10 | 0 | 67° – 79° |
| September | 76° | 55° | 3.3" | 0 | 9 | 0 | 59° – 70° |
| October | 63° | 43° | 3.5" | 0 | 11 | 0 | 49° – 59° |
| November | 49° | 33° | 2.5" | 0.6" | 9 | 0 | 33° – 49° |
| December | 37° | 23° | 2.1" | 9.7" | 13 | 14 | 17° – 40° |
| Year | 59° | 41° | 37.9" | 42.3" | 133 | 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 River Forest
River Forest 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 133 days a year. Snow covers the ground about 55 days of the year.
About 193 frost-free days a year
In half of years the last 32° night comes by April 16 and the first one by October 28. That leaves about 193 frost-free days for gardens, longer than 67% of U.S. towns.
Heating and cooling a home in River Forest
Engineers use “degree days” to estimate how hard a furnace or air conditioner works. In River Forest, 86% of that work is heating and 14% 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.
River Forest and its neighbors
River Forest borders 5 towns with climate data. January nights across them vary by 0.2°. Proviso has both the coldest January nights (17°) and the hottest July afternoons (84°). River Forest’s January low is 17° and its July high 84°.
Temperatures and rain come from NOAA’s 5 km grid, so each town gets its own value.
How River Forest 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 River Forest averaged 1.4° warmer than the 1900s. The biggest change is in December (+2.6°). The shift is larger than in 65% of U.S. towns.
Change by month1991–2020 average minus 1901–2000 average, at River Forest’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 16° to 39°. June is the most reliable, staying within 9°.
Common questions about River Forest’s climate
What is the coldest month in River Forest?
January, with a typical high of 32° and a low of 17°.
What is the hottest month in River Forest?
July, with a typical high of 84° and a low of 65°. About 17 days a year reach 90°.
How much snow does River Forest get?
About 42 inches in a normal winter, most of it in February.
When is the first frost in River Forest?
In half of years the first 32° night comes by October 28, and the last spring frost by April 16.
What is the rainiest month in River Forest?
May, 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 River Forest itself (about a 3-mile square). Snow, frost dates and day counts come from NOAA’s weather station at Oak Brook 2w, IL (9 mi, snow) and Chicago Ohare Intl Airport, IL (9 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.