Climate normals · 1970–2000
O'Fallon Climate
O'Fallon is a city in United States (MO) with a population of about 85,040. Its average annual temperature is 12.8°C (55°F), with roughly 957 mm of rain per year.
12.8°C
Avg Temp
957
Precip (mm/yr)
Jul
Hottest Month
Jan
Coldest Month
O'Fallon Climate
O'Fallon has an average annual temperature of 12.8°C (55°F) and receives about 957 mm of precipitation per year. The warmest month is July and the coldest is January. Figures are 1970–2000 climate normals.
12.8°C
Avg Temp
957
Precip (mm/yr)
Jul
Hottest Month
Jan
Coldest Month
| Month | Avg (°C/°F) | Precip |
|---|---|---|
| January | -2° / 29° | 45 mm |
| February | 1° / 34° | 51 mm |
| March | 7° / 44° | 85 mm |
| April | 13° / 55° | 94 mm |
| May | 18° / 65° | 107 mm |
| June | 23° / 74° | 89 mm |
| July | 26° / 79° | 100 mm |
| August | 25° / 76° | 80 mm |
| September | 21° / 69° | 82 mm |
| October | 14° / 57° | 75 mm |
| November | 7° / 45° | 81 mm |
| December | 1° / 33° | 68 mm |
1970–2000 normals from WorldClim 2.1 (~9 km grid). Precipitation can be less precise near mountains or coastlines, where rainfall varies sharply over short distances.
Best time to visit O'Fallon
The most comfortable months to visit O'Fallon are typically September, June and August, when temperatures are mildest and rainfall is relatively low. The hottest month is July (around 32°C high). The coldest is January (near -7°C low). May is usually the wettest month.
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Frequently Asked Questions
The most comfortable months to visit O'Fallon are typically September, June and August, when temperatures are mildest and rainfall is relatively low (1970–2000 climate normals).
O'Fallon, United States has an average annual temperature of 12.8°C and about 957 mm of precipitation per year. The warmest month is July and the coldest is January.
In July, the hottest month, daily highs in O'Fallon average about 32°C (90°F).
Monthly climate normals (1970–2000) sampled from WorldClim 2.1 at ~9 km resolution. Humidity derived from vapor pressure. City coordinates and population from GeoNames.