Crystal Lake, IL climate
Crystal Lake has cold, snowy winters and pleasant summers. A typical July afternoon reaches 83°, a January night drops to 14°, and about 35 inches of snow falls in a normal winter.
NOAA 1991-2020 climate normals Updated once a decadeWhat a year in Crystal Lake feels like
Winter
Spring
Summer
Fall
Crystal 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 | 29° | 14° | 1.8" | 10.0" | 9 | 18 | 11° – 33° |
| February | 34° | 17° | 1.8" | 9.0" | 8 | 17 | 13° – 37° |
| March | 46° | 27° | 2.2" | 4.4" | 8 | 7 | 27° – 51° |
| April | 58° | 36° | 3.8" | 1.2" | 11 | 1 | 39° – 54° |
| May | 70° | 47° | 4.6" | 0 | 12 | 0 | 53° – 65° |
| June | 79° | 57° | 4.7" | 0 | 10 | 0 | 65° – 73° |
| July | 83° | 62° | 4.0" | 0 | 9 | 0 | 67° – 79° |
| August | 81° | 60° | 3.9" | 0 | 9 | 0 | 65° – 77° |
| September | 74° | 53° | 3.5" | 0 | 8 | 0 | 58° – 68° |
| October | 62° | 41° | 3.2" | 0.2" | 9 | 0 | 47° – 57° |
| November | 47° | 30° | 2.4" | 1.6" | 9 | 2 | 30° – 47° |
| December | 34° | 20° | 2.0" | 8.7" | 9 | 11 | 14° – 38° |
| Year | 58° | 39° | 37.9" | 35.1" | 110 | 54 |
“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 Crystal Lake
Crystal Lake gets 38 inches of rain and melted snow a year. June is the wettest month and January the driest. Rain or snow falls on about 110 days a year. Snow covers the ground about 54 days of the year.
About 179 frost-free days a year
In half of years the last 32° night comes by April 25 and the first one by October 22. That leaves about 179 frost-free days for gardens, longer than 51% of U.S. towns.
Heating and cooling a home in Crystal Lake
Engineers use “degree days” to estimate how hard a furnace or air conditioner works. In Crystal Lake, 89% of that work is heating and 11% 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.
Crystal Lake and its neighbors
Crystal Lake borders 7 towns with climate data. January nights across them vary by 0.6°. Dorr has the coldest January nights (14°) and Lake in the Hills the hottest July afternoons (83°). Crystal Lake’s January low is 14° and its July high 83°.
Temperatures and rain come from NOAA’s 5 km grid, so each town gets its own value.
How Crystal 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 Crystal Lake averaged 1.1° warmer than the 1900s. The biggest change is in December (+2.5°). The shift is smaller than in 57% of U.S. towns.
Change by month1991–2020 average minus 1901–2000 average, at Crystal 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 13° to 37°. June is the most reliable, staying within 8°.
Common questions about Crystal Lake’s climate
What is the coldest month in Crystal Lake?
January, with a typical high of 29° and a low of 14°.
What is the hottest month in Crystal Lake?
July, with a typical high of 83° and a low of 62°. About 22 days a year reach 90°.
How much snow does Crystal Lake get?
About 35 inches in a normal winter, most of it in January.
When is the first frost in Crystal Lake?
In half of years the first 32° night comes by October 22, and the last spring frost by April 25.
What is the rainiest month in Crystal Lake?
June, with 4.7 inches of rain and melted snow. The year totals 38 inches.
Temperatures and rainfall come from NOAA’s gridded climate normals for Crystal Lake itself (about a 3-mile square). Snow, frost dates and day counts come from NOAA’s weather station at Crystal Lake 4nw, IL (4 mi) away. Normals are 30-year averages, not a forecast. Source: NOAA NCEI U.S. Climate Normals, 1991–2020 and 1901–2000.