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Weather & Climate
Williamson County, Illinois, United States
Overview
Available climate summaries for Williamson County. Origins and reference periods are unverified; stored values may include AI estimates. Treat these as estimates until independently verified.
Key Metrics
Annual Avg
13.8°C
Summer Avg
25°C
Winter Avg
1.6°C
Record High
42.7°C
Record Low
-20.3°C
Annual Precipitation
1230.2 mm
Avg Humidity
77%
Summer Humidity
75%
Winter Humidity
83%
Monthly Averages
| Month | High (°C) | Avg (°C) | Low (°C) | Rain (mm) | Humidity (%) | Sunshine (h) | Wind (kph) |
|---|---|---|---|---|---|---|---|
| Jan | 21.8° | 0.3° | -20.3° | 78.4 | 83% | 65 | 54.6 |
| Feb | 22.2° | 2° | -19.7° | 91 | 82% | 78 | 53.3 |
| Mar | 26.1° | 7.9° | -14.8° | 120.6 | 81% | 118 | 56.1 |
| Apr | 29.4° | 14.1° | -5.2° | 131.4 | 78% | 153 | 46.8 |
| May | 32.5° | 19.1° | 1.9° | 129.9 | 80% | 177 | 43.2 |
| Jun | 42.4° | 23.9° | 6.2° | 100.2 | 78% | 194 | 42.3 |
| Jul | 42.7° | 25.7° | 11.9° | 110 | 76% | 194 | 30 |
| Aug | 40.8° | 25.4° | 10.5° | 84.3 | 71% | 176 | 40.4 |
| Sep | 38.1° | 21.8° | 4° | 77.7 | 69% | 143 | 53.4 |
| Oct | 34.5° | 14.6° | -3.4° | 102 | 71% | 110 | 42.8 |
| Nov | 27.3° | 7.7° | -10.4° | 100.5 | 77% | 74 | 48.6 |
| Dec | 22.6° | 2.5° | -19.3° | 104.2 | 83% | 57 | 46.8 |
Data sources
Estimates and unverified origins
Oyster List climate data - Climate origins are unverified. Available methods include historical APIs and AI estimates; stored rows do not identify the original dataset, reference period, or model for each value. Treat these summaries as estimates until independently verified. Record updated 2026-03-22.
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