Lake Petersburg, IL Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for Lake Petersburg, a community in Menard County, Illinois.
Today
61°F
Slight Chance Drizzle
A slight chance of drizzle. Mostly cloudy, with a high near 61. West southwest wind 12 to 15 mph, with gusts as high as 26 mph.
7-day forecast for Lake Petersburg
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Today | 61°F | Slight Chance Drizzle | 12 to 15 mph WSW | 10% |
| Tonight | 42°F | Slight Chance Drizzle then Mostly Cloudy | 12 mph WSW | 10% |
| Thursday | 60°F | Mostly Cloudy | 10 to 14 mph W | 14% |
| Thursday Night | 43°F | Mostly Cloudy | 5 to 8 mph NW | 13% |
| Friday | 54°F | Partly Sunny | 10 mph N | 4% |
| Friday Night | 32°F | Partly Cloudy | 1 to 7 mph NNW | 0% |
| Saturday | 53°F | Mostly Sunny | 1 to 5 mph NNW | 0% |
| Saturday Night | 32°F | Mostly Clear | 2 mph WNW | 1% |
| Sunday | 58°F | Sunny | 2 to 7 mph W | 1% |
| Sunday Night | 34°F | Clear | 3 mph WSW | 1% |
| Monday | 64°F | Sunny | 1 to 7 mph SW | 0% |
| Monday Night | 39°F | Clear | 5 mph SW | 0% |
| Tuesday | 66°F | Sunny | 5 mph WNW | 1% |
| Tuesday Night | 39°F | Mostly Clear | 2 mph NNE | 1% |
Forecast source: National Weather Service (api.weather.gov) for Lake Petersburg (39.984, -89.856). Updated through the day.
Growing snapshot for Lake Petersburg
Last spring frost
Apr 13
First fall frost
Oct 21
Growing season
189 days
Hardiness zone
6a
More local growing data for Lake 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 Lake Petersburg). Frost dates are 1991–2020 averages, not a forecast. Page updated Nov 4, 2026.