Chester, IL Weather & Climate Normals
What a normal year in Chester actually looks like
On the 30-year record NOAA keeps for Chester, IL, the comfort score comes out to 44/100, strongly seasonal: Comfortable weather is limited to a shorter window; summers, winters, or precipitation swing wide. Only 4 months a year land in the 55–75°F range this site treats as mild.
How much Chester's weather actually swings
Average temperatures in Chester run from 32°F in Jan up to 79°F in Jul, a 46.5°F seasonal swing, one of the widest gaps in this dataset.
Chester, month by month
| Month | Avg high | Avg low | Precip | Snow |
|---|---|---|---|---|
| Jan | 40°F | 24°F | 2.73in | 1.4in |
| Feb | 46°F | 27°F | 2.35in | 1.5in |
| Mar | 56°F | 35°F | 3.41in | 0.1in |
| Apr | 68°F | 44°F | 4.67in | 0in |
| May | 77°F | 55°F | 5.18in | 0in |
| Jun | 86°F | 64°F | 4.14in | 0in |
| Jul | 89°F | 68°F | 4.13in | 0in |
| Aug | 88°F | 66°F | 3.34in | 0in |
| Sep | 81°F | 58°F | 2.94in | 0in |
| Oct | 70°F | 46°F | 3.07in | 0in |
| Nov | 56°F | 37°F | 4.01in | 0.4in |
| Dec | 44°F | 28°F | 2.85in | 0.9in |
If you're timing a visit, Apr, May, Sep, and Oct are Chester's mildest stretch; if you're moving there, you should plan around Jul's heat and Jan's cold instead.
How wet Chester actually gets
Over a typical year, Chester sees about 42.82in of precipitation a year across roughly 97 days with measurable rain or snow, with 4.3in of snow a year.
Chester against the rest of the country
Out of 4876 cities scored here, Chester comes in at 3900; within IL alone it ranks 221 of 330. Population is about 6,759.
Checking the actual forecast
These figures come from Kaskaskia Rvr Navigation Lock, IL US, the NOAA station 7.6 miles from Chester, averaged over 30 years, not tomorrow's forecast.
More on how this is worked out
Why some cities show no snow or rain figure · What a 30-year climate normal actually is