St. Jacob, IL Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for St. Jacob, a village in Madison County, Illinois.
This Afternoon
96°F
Mostly Cloudy
Mostly cloudy, with a high near 96. Heat index values as high as 100. Southwest wind around 6 mph.
7-day forecast for St. Jacob
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| This Afternoon | 96°F | Mostly Cloudy | 6 mph SW | 2% |
| Tonight | 72°F | Partly Cloudy | 5 mph S | 2% |
| Sunday | 93°F | Mostly Sunny then Slight Chance Showers And Thunderstorms | 2 to 7 mph W | 19% |
| Sunday Night | 66°F | Chance Showers And Thunderstorms then Showers And Thunderstorms Likely | 5 to 9 mph N | 63% |
| Monday | 81°F | Showers And Thunderstorms Likely | 6 to 10 mph NE | 63% |
| Monday Night | 60°F | Chance Showers And Thunderstorms | 6 to 10 mph NE | 45% |
| Tuesday | 72°F | Slight Chance Rain Showers then Partly Sunny | 8 to 13 mph N | 17% |
| Tuesday Night | 55°F | Mostly Cloudy | 5 to 13 mph N | 1% |
| Wednesday | 74°F | Mostly Sunny | 7 to 10 mph N | 0% |
| Wednesday Night | 55°F | Partly Cloudy | 2 to 9 mph N | 0% |
| Thursday | 76°F | Mostly Sunny | 3 to 7 mph N | 0% |
| Thursday Night | 58°F | Mostly Cloudy then Slight Chance Rain Showers | 2 to 7 mph NE | 15% |
| Friday | 79°F | Slight Chance Rain Showers | 2 to 7 mph NE | 17% |
| Friday Night | 58°F | Slight Chance Rain Showers then Partly Cloudy | 2 to 7 mph NE | 17% |
Forecast source: National Weather Service (api.weather.gov) for St. Jacob (38.718, -89.763). Updated through the day.
Growing snapshot for St. Jacob
Last spring frost
Apr 12
First fall frost
Oct 20
Growing season
189 days
Hardiness zone
7a
More local growing data for St. Jacob: nearby ZIP 62281 weather · frost dates · planting calendar · Illinois frost dates
Nearby towns & communities
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Alton
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Collinsville
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Madison
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Maryville
Mitchell
Moro
New Douglas
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Rosewood Heights
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Wood River
Climate data from the nearest NOAA station, Belleville Siu Rsch, Il (13.4 mi from St. Jacob). Frost dates are 1991–2020 averages, not a forecast. Page updated Sep 19, 2026.