O'Fallon, IL weather
Today, hourly and 7-day forecast, sunrise and sunset, and the normal climate month by month
Weather in O'Fallon now
Loading the National Weather Service forecast…
O'Fallon weather by the hour
O'Fallon weather for the next 7 days
Source: National Weather Service (NOAA) · forecast for the coordinates of O'Fallon.
This week in O'Fallon
Sunrise, sunset and moon in O'Fallon
What is the weather usually like in O'Fallon?
Köppen climate classification, calculated from the 1991–2020 normals
- Julywarmest month · 90°F average high
- Januarycoldest month · 24°F average low
- 43.4 inprecipitation per year · 1,101 mm
- 11.2 insnowfall per year · 28 cm
Average high and low temperature (°F)
Average precipitation (inches)
Best time to visit O'Fallon: April–May and September–October, with mild temperatures and fewer rainy days.
Source: NOAA NCEI U.S. Climate Normals 1991–2020, station BELLEVILLE SIU RSCH, IL US (USW00013802), adjusted for the elevation of O'Fallon.
O'Fallon weather month by month
Sunrise and sunset in O'Fallon through the year
| Month | Sunrise | Sunset | Daylight |
|---|---|---|---|
| January | 7:14 AM | 5:04 PM | 9 h 49 min |
| February | 6:48 AM | 5:38 PM | 10 h 50 min |
| March | 7:08 AM | 7:07 PM | 11 h 59 min |
| April | 6:21 AM | 7:37 PM | 13 h 16 min |
| May | 5:46 AM | 8:06 PM | 14 h 20 min |
| June | 5:33 AM | 8:27 PM | 14 h 54 min |
| July | 5:46 AM | 8:25 PM | 14 h 38 min |
| August | 6:12 AM | 7:55 PM | 13 h 42 min |
| September | 6:40 AM | 7:09 PM | 12 h 29 min |
| October | 7:07 AM | 6:22 PM | 11 h 15 min |
| November | 6:40 AM | 4:48 PM | 10 h 7 min |
| December | 7:08 AM | 4:41 PM | 9 h 32 min |
Times for the 15th of each month, local time (America/Chicago).
What is the weather like in O'Fallon?
O'Fallon has a humid subtropical climate. The warmest month is July, with an average high of 90°F (32°C), and the coldest is January, with average lows of 24°F (-5°C).
It gets about 43.4 inches (1,101 mm) of precipitation a year. The wettest month is May and the driest is February. Snow is common: about 11 inches fall in an average year.
The best time to visit O'Fallon is April–May and September–October. At 538 ft of elevation, nights are mild most of the year. The live forecast on this page comes from the National Weather Service and the climate averages from NOAA’s 1991–2020 U.S. Climate Normals.
More about O'Fallon
Weather in towns near O'Fallon
Questions about the weather in O'Fallon
What is the hottest month in O'Fallon?
July, with an average high of 90°F (32°C).
What is the coldest month in O'Fallon?
January, with an average low of 24°F (-5°C).
How much does it rain in O'Fallon?
About 43.4 inches (1,101 mm) a year; the wettest month is May.
Does it snow in O'Fallon?
Yes, about 11 inches of snow fall in an average year.
When is the best time to visit O'Fallon?
April–May and September–October, when temperatures are most pleasant and rainy days are fewer.
What climate does O'Fallon have?
Humid subtropical (Köppen Cfa).
What is the weather like in O'Fallon in November?
Highs average 58°F and lows 37°F, with about 3.6 inches of precipitation.
What time is sunrise in O'Fallon?
Around 6:40 AM in mid-November, and sunset around 4:48 PM. Today’s exact times are shown above.
Where does this O'Fallon weather forecast come from?
From the National Weather Service (NOAA), the official U.S. weather agency, for the exact coordinates of O'Fallon.
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