St. Jacob, IL Weather & Growing Conditions
Overnight
55°F
Slight Chance Drizzle
A slight chance of drizzle. Mostly cloudy, with a low around 55. Southwest wind around 10 mph. Chance of precipitation is 20%.
7-day forecast
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Overnight | 55°F | Slight Chance Drizzle | 10 mph SW | 18% |
| Wednesday | 60°F | Slight Chance Drizzle | 8 to 15 mph W | 12% |
| Wednesday Night | 44°F | Partly Cloudy | 6 mph W | 0% |
| Thursday | 64°F | Sunny | 5 to 12 mph W | 0% |
| Thursday Night | 45°F | Mostly Cloudy | 5 mph NW | 2% |
| Friday | 57°F | Partly Sunny | 6 to 13 mph NW | 2% |
| Friday Night | 36°F | Partly Cloudy | 2 to 8 mph N | 0% |
| Saturday | 55°F | Mostly Sunny | 5 mph N | 0% |
| Saturday Night | 34°F | Partly Cloudy | 2 mph NW | 0% |
| Sunday | 60°F | Sunny | 1 to 7 mph NW | 1% |
| Sunday Night | 35°F | Clear | 0 to 3 mph NW | 0% |
| Monday | 65°F | Sunny | 0 to 6 mph SW | 0% |
| Monday Night | 40°F | Clear | 2 mph SW | 0% |
| Tuesday | 68°F | Sunny | 5 mph W | 1% |
Forecast source: National Weather Service (api.weather.gov). Updated through the day.
Growing snapshot for St. Jacob, IL
Last spring frost
Apr 12
First fall frost
Oct 20
Growing season
189 days
Hardiness zone
7a
Explore more for St. Jacob, IL: full frost dates · planting calendar · Illinois frost dates
Climate data from the nearest NOAA station, Belleville Siu Rsch, Il (13.4 mi). Frost dates are 1991–2020 averages, not a forecast. Page updated Nov 4, 2026.