Petersburg, IL Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for Petersburg, a city in Menard County, Illinois.
Today
88°F
Sunny
Sunny, with a high near 88. South wind around 6 mph.
7-day forecast for Petersburg
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Today | 88°F | Sunny | 6 mph S | 0% |
| Tonight | 68°F | Partly Cloudy | 6 mph SSE | 4% |
| Wednesday | 87°F | Slight Chance Rain Showers then Chance Showers And Thunderstorms | 7 mph S | 26% |
| Wednesday Night | 67°F | Chance Showers And Thunderstorms then Showers And Thunderstorms | 5 mph SSE | 78% |
| Thursday | 82°F | Showers And Thunderstorms then Chance Showers And Thunderstorms | 5 mph S | 78% |
| Thursday Night | 65°F | Slight Chance Showers And Thunderstorms | 3 mph SSE | 16% |
| Friday | 84°F | Mostly Sunny | 2 mph SSW | 11% |
| Friday Night | 66°F | Slight Chance Showers And Thunderstorms | 2 mph S | 19% |
| Saturday | 87°F | Slight Chance Showers And Thunderstorms then Mostly Sunny | 2 to 6 mph SSW | 19% |
| Saturday Night | 70°F | Mostly Clear | 3 to 7 mph S | 10% |
| Sunday | 90°F | Sunny | 7 to 10 mph SSW | 5% |
| Sunday Night | 72°F | Partly Cloudy | 9 mph S | 14% |
| Monday | 90°F | Mostly Sunny | 10 mph SSW | 14% |
| Monday Night | 73°F | Slight Chance Showers And Thunderstorms | 9 mph SSW | 26% |
Forecast source: National Weather Service (api.weather.gov) for Petersburg (40.014, -89.845). Updated through the day.
Growing snapshot for Petersburg
Last spring frost
Apr 13
First fall frost
Oct 21
Growing season
189 days
Hardiness zone
6a
More local growing data for Petersburg: nearby ZIP 62675 weather · frost dates · planting calendar · Illinois frost dates
Nearby towns & communities
Climate data from the nearest NOAA station, Petersburg 1E, Il (1.9 mi from Petersburg). Frost dates are 1991–2020 averages, not a forecast. Page updated Aug 4, 2026.