Climate almanac
O'Fallon
Illinois, US · 38.59°, -89.91°
What is the climate like in O'Fallon?
O'Fallon is warmest in July, when daily highs average 89°F (32°C), and coolest in January, when lows fall to about 27°F (-3°C). The wettest month is typically April and the driest is December; the year sees roughly 47 in of precipitation.
- Warmest monthJuly — average high 89°F (32°C)
- Coolest monthJanuary — average low 27°F (-3°C)
- Wettest monthApril (5.7 in)
- Driest monthDecember (2.8 in)
- Annual precipitation47 in