St. Peter, IL Weather & Growing Conditions
Today
85°F
Sunny
Sunny, with a high near 85. South wind around 2 mph.
7-day forecast
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Today | 85°F | Sunny | 2 mph S | 0% |
| Tonight | 64°F | Mostly Clear | 2 mph SE | 0% |
| Wednesday | 87°F | Sunny | 2 mph S | 2% |
| Wednesday Night | 69°F | Partly Cloudy then Chance Showers And Thunderstorms | 3 mph S | 38% |
| Thursday | 84°F | Chance Showers And Thunderstorms then Showers And Thunderstorms Likely | 6 mph SW | 59% |
| Thursday Night | 68°F | Chance Showers And Thunderstorms | 3 mph SE | 54% |
| Friday | 85°F | Chance Showers And Thunderstorms | 1 to 5 mph SW | 45% |
| Friday Night | 68°F | Chance Showers And Thunderstorms | 1 mph S | 25% |
| Saturday | 86°F | Chance Showers And Thunderstorms | 3 mph SW | 25% |
| Saturday Night | 70°F | Mostly Clear | 3 mph S | 14% |
| Sunday | 88°F | Sunny | 5 to 9 mph SW | 8% |
| Sunday Night | 72°F | Mostly Clear | 8 mph S | 6% |
| Monday | 90°F | Mostly Sunny | 8 mph SW | 7% |
| Monday Night | 73°F | Slight Chance Showers And Thunderstorms | 7 mph SW | 16% |
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 Aug 4, 2026.