St. Marys, IL Weather Forecast

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St. Marys, IL Weather Forecast

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St. Marys IL weather  - Clear - 71°F
Clear
71°F
Updated 3:20 am
Feels Like 69°F
Humidity 59%
Wind SE 5 mph
Barometer  29.93 in
Dew Point 56°F
St. Marys IL weather  - Clear - 22°C
Clear
22°C
Updated 3:20 am
Feels Like 21°C
Humidity 59%
Wind SE 8 km/h
Barometer  101.3 kPa
Dew Point 13°C

St. Marys Weather Forecast

REST OF TONIGHT THURSDAY THURSDAY NIGHT FRIDAY FRIDAY NIGHT SATURDAY SUNDAY SUNDAY NIGHT MONDAY MONDAY NIGHT TUESDAY TUESDAY NIGHT
St. Marys, IL Weather - Rest Of Tonight Mostly Cloudy St. Marys, IL Weather - Thursday Chance Of T-Storm St. Marys, IL Weather - Thursday Night Chance Of T-Storm St. Marys, IL Weather - Friday Showers St. Marys, IL Weather - Friday Night Partly Cloudy St. Marys, IL Weather - Saturday Mostly Clear St. Marys, IL Weather - Sunday Mostly Clear St. Marys, IL Weather - Sunday Night Clear St. Marys, IL Weather - Monday Clear St. Marys, IL Weather - Monday Night Clear St. Marys, IL Weather - Tuesday Clear St. Marys, IL Weather - Tuesday Night Mostly Clear
Mostly Cloudy Chance of T-Storm Chance of T-Storm Showers Partly Cloudy Mostly Clear Mostly Clear Clear Clear Clear Clear Mostly Clear
Lo: 69°FLo: 21°C Hi: 89°FHi: 32°C
Lo: 61°FLo: 16°C Hi: 69°FHi: 21°C
Lo: 49°FLo: 9°C Hi: 71°FHi: 22°C
Lo: 49°FLo: 9°C
Hi: 71°FHi: 22°C
Lo: 49°FLo: 9°C
Hi: 70°FHi: 21°C
Lo: 49°FLo: 9°C
Hi: 70°FHi: 21°C
Lo: 49°FLo: 9°C
Hi: 69°FHi: 21°C
Lo: 41°FLo: 5°C
Hi: 69°FHi: 21°C
Lo: 41°FLo: 5°C
Hi: 75°FHi: 24°C
Lo: 45°FLo: 7°C
POP: 20% POP: 100% POP: 70%
POP = Probability of Precipitation.
Weather Outlook Updated: 127 AM CDT Thu Oct 01 2026 St. Marys, IL Weather - WeatherWorld.com

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Issued: 301 AM CDT Thu Oct 1 2026

Key Messages

  • Multiple rounds of widespread rain will track across the region this afternoon through Friday morning. Broad rainfall totals of 0.25 to 0.75 inches are expected, though localized heavy rain bands could produce isolated amounts of 2 to 3 inches.
  • Temperatures drop significantly heading into the weekend, with highs in the upper 60s Friday and Saturday, and overnight lows falling into the 40s.
  • Crisp, quiet autumn weather will remain across the region through early next week before temper...