See exactly when rain will start and stop with a minute-by-minute precipitation nowcast for the next hour.
25°
Overcast
Feels Like: 6°
Min: 24°
Max: 35°
The next few hours will be overcast, with today reaching 35°C and dropping to 8°C. The coming days will be mostly clear until evening, returning overnight.
Compare today's weather with yesterday's data and track temperature trends over time.
Hourly Forecast
Daylight Hours
06:47
Sunrise
18:59
Sunset
Moon
Waxing Crescent
12:34
Moonrise
21:12
Moonset
Daily Forecast
Today
Thursday
Friday
Saturday
Sunday
Monday
Tuesday
Wednesday
Thursday
Friday
Air Quality Data Available
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UV Index
Humidity
Weather in O'Fallon today, September 16, 2026
Expect a muted, overcast feel in O'Fallon on September 16, 2026 as cloud persists. Brighter breaks, if they arrive, should stay brief. The first half of the day looks overcast, as cloud amounts reach about 100% around 07:00. Brighter weather, if it comes, waits until later.
Expect highs of 35°C and cooler readings close to 24°C. Relative humidity sits between 43% and 90%, reaching its peak around 23:00. Expect gentle winds, highest near 17:00 at 9.2 km/h.
The afternoon keeps an overcast feel, as cloud reaches about 100% around 17:00. Outdoor plans may still want a flexible backup. Expect visibility near 16.0 km, with poorer spells close to 14.6 km. Expect sunrise at 06:47, sunset at 18:59, and 12 hours 11 minutes of sunlight today overall.
Overall, O'Fallon on September 16, 2026 stays grey and muted, so outdoor plans may want a flexible backup even with a high near 35°C.
Frequently asked questions about weather in O'Fallon
How warm does it get in O'Fallon?
The warmest month in O'Fallon is July, with average high temperatures of 32°C. The average temperature during this period is around 27°C.
How cold does it get in O'Fallon?
The coldest month in O'Fallon is January, with average low temperatures of -3°C. The average temperature during this period is around 0°C.
What is the wettest time of year in O'Fallon?
The wettest month in O'Fallon is April, with an average of 144mm of precipitation.
What is the driest time of year in O'Fallon?
The driest month in O'Fallon is December, with an average of 69mm of precipitation.
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