St. Peter, IL Weather & Growing Conditions
Today
95°F
Mostly Sunny
Mostly sunny, with a high near 95. Southwest wind around 6 mph.
7-day forecast
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Today | 95°F | Mostly Sunny | 6 mph SW | 10% |
| Tonight | 71°F | Partly Cloudy | 5 mph SW | 4% |
| Sunday | 92°F | Mostly Sunny then Slight Chance Showers And Thunderstorms | 2 to 6 mph W | 31% |
| Sunday Night | 64°F | Chance Showers And Thunderstorms | 5 to 8 mph NE | 53% |
| Monday | 77°F | Showers And Thunderstorms Likely | 7 to 12 mph NE | 71% |
| Monday Night | 57°F | Showers And Thunderstorms Likely | 6 to 12 mph NE | 71% |
| Tuesday | 70°F | Slight Chance Showers And Thunderstorms | 10 mph NE | 22% |
| Tuesday Night | 54°F | Mostly Cloudy | 5 to 10 mph N | 12% |
| Wednesday | 73°F | Mostly Sunny | 6 to 9 mph N | 5% |
| Wednesday Night | 54°F | Partly Cloudy | 2 to 8 mph N | 2% |
| Thursday | 75°F | Mostly Sunny | 3 to 8 mph N | 2% |
| Thursday Night | 55°F | Partly Cloudy | 2 to 7 mph NE | 3% |
| Friday | 77°F | Mostly Sunny | 3 to 8 mph NE | 3% |
| Friday Night | 54°F | Partly Cloudy | 3 to 7 mph NE | 2% |
Forecast source: National Weather Service (api.weather.gov). Updated through the day.
Growing snapshot for St. Peter, IL
Last spring frost
Apr 3
First fall frost
Oct 24
Growing season
202 days
Hardiness zone
6b
Explore more for St. Peter, IL: full frost dates · planting calendar · Illinois frost dates
Climate data from the nearest NOAA station, Brownstown 4 Sw, Il (7.2 mi). Frost dates are 1991–2020 averages, not a forecast. Page updated Sep 19, 2026.