Saint Clair County, IL Weather Forecast for 5-Days

Updated: Fri Feb 13th 2026 5:00 PM CST

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Saint Clair County, IL Weather – 2-13 – Sunny
64° / 32°
Sunny
Saint Clair County is set for sunshine with temperatures peaking at 64°F and dipping to 32°F. Wind will be moderate, blowing around 13mph on average and gusts of 18.8mph at 6 PM. Humidity levels should be comfortable, sitting around 56% on average, the maximum being 62% at 11 PM and 30% being its lowest at 5 PM. Barometric pressure is its highest of 30.14inHg at 7 PM, a lowest point of 30.12inHg at 5 PM with an avg 30.13inHg.
Saint Clair County, IL Weather – 2-14 – Heavy Rain
49° / 37°

Weather Tomorrow

Heavy Rain
In Saint Clair County, rain is likely with a high near 49°F and a low around 37°F. The chance of rain is 88% with an estimated 0.84in. Wind will be moderate, blowing around 14mph on average and gusts of 20.5mph at 6 PM. High humidity with average of 86% is anticipated, the maximum being 98% at 10 PM and 64% being its lowest at 5 AM. Barometric pressure is its highest of 30.15inHg at 10 AM, a lowest point of 29.89inHg at 11 PM with an avg 30.05inHg.
Saint Clair County, IL Weather – 2-15 – Heavy Rain
49° / 44°
Heavy Rain
Rain is in the forecast for Saint Clair County, with a high of 49°F and a low of 44°F. The chance of rain is 83% with an estimated 2.4in. Wind will be moderate, blowing around 15mph on average and gusts of 18.7mph at 3 AM. High humidity with average of 97% is anticipated, the maximum being 98% at 10 PM and 92% being its lowest at 3 PM. Barometric pressure is its highest of 30.03inHg at 10 PM, a lowest point of 29.83inHg at 4 AM with an avg 29.91inHg.
Saint Clair County, IL Weather – 2-16 – Fog
53° / 43°
Fog
Saint Clair County is set for fog with temperatures peaking at 53°F and dipping to 43°F. Wind will be moderate, blowing around 12mph on average and gusts of 17.9mph at 6 PM. High humidity with average of 91% is anticipated, the maximum being 99% at 6 AM and 76% being its lowest at 8 PM. Barometric pressure is its highest of 30.1inHg at 10 AM, a lowest point of 29.95inHg at 12 AM with an avg 30.05inHg.
Saint Clair County, IL Weather – 2-17 – Partly Cloudy
62° / 44°
Partly Cloudy
It will be cloudy in Saint Clair County, with a high of 62°F and a low of 44°F. Winds will be strong at speeds peaking at 23mph and gusts of 37.2mph at 8 PM. The humidity will be on the higher side, averaging about 78%, the maximum being 91% at 6 AM and 67% being its lowest at 2 PM. Barometric pressure is its highest of 30.04inHg at 1 AM, a lowest point of 29.7inHg at 11 PM with an avg 29.88inHg.
Saint Clair County, IL Weather – 2-18 – Overcast
66° / 55°
Overcast
Daytime highs will reach 66°F with lows dropping to 55°F in Saint Clair County, where it will be overcast. Wind will be moderate, blowing around 19mph on average and gusts of 31.6mph at 12 AM. Humidity levels should be comfortable, sitting around 59% on average, the maximum being 80% at 6 AM and 28% being its lowest at 3 PM. Barometric pressure is its highest of 29.87inHg at 11 PM, a lowest point of 29.69inHg at 12 AM with an avg 29.79inHg.

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