Petersburg, IL Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for Petersburg, a city in Menard County, Illinois.
This Afternoon
86°F
Mostly Sunny
Mostly sunny, with a high near 86. East wind around 8 mph.
7-day forecast for Petersburg
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| This Afternoon | 86°F | Mostly Sunny | 8 mph E | 8% |
| Tonight | 71°F | Partly Cloudy | 8 mph ESE | 5% |
| Saturday | 91°F | Partly Sunny | 8 mph SW | 12% |
| Saturday Night | 69°F | Mostly Cloudy then Chance Showers And Thunderstorms | 7 mph SSW | 35% |
| Sunday | 83°F | Showers And Thunderstorms Likely | 2 to 10 mph NNW | 62% |
| Sunday Night | 60°F | Showers And Thunderstorms Likely then Chance Showers And Thunderstorms | 8 to 12 mph NE | 69% |
| Monday | 70°F | Showers And Thunderstorms Likely | 12 mph NE | 69% |
| Monday Night | 55°F | Chance Showers And Thunderstorms | 8 to 12 mph NE | 47% |
| Tuesday | 67°F | Chance Rain Showers then Mostly Cloudy | 10 mph NE | 32% |
| Tuesday Night | 51°F | Mostly Cloudy | 5 to 9 mph NNE | 4% |
| Wednesday | 71°F | Partly Sunny | 8 mph NNE | 3% |
| Wednesday Night | 53°F | Partly Cloudy | 2 to 7 mph NNE | 0% |
| Thursday | 71°F | Mostly Sunny | 3 to 7 mph NNE | 3% |
| Thursday Night | 55°F | Partly Cloudy | 2 to 6 mph NNE | 4% |
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 Sep 19, 2026.