Harman US

St. Johns, IL Weather & Growing Conditions

Local forecast, frost dates, hardiness zone and planting guidance for St. Johns, a village in Perry County, Illinois.

Today
99°F
Sunny
Sunny. High near 99, with temperatures falling to around 97 in the afternoon. West southwest wind 3 to 8 mph.

7-day forecast for St. Johns

WhenTempForecastWindPrecip
Today 99°F Sunny 3 to 8 mph WSW 2%
Tonight 72°F Mostly Clear 5 mph SSW 2%
Sunday 97°F Mostly Sunny 3 to 7 mph WSW 2%
Sunday Night 68°F Mostly Cloudy then Chance Showers And Thunderstorms 6 mph N 41%
Monday 84°F Showers And Thunderstorms Likely 5 to 10 mph NNE 61%
Monday Night 60°F Showers And Thunderstorms Likely then Slight Chance Showers And Thunderstorms 6 to 10 mph NNE 61%
Tuesday 75°F Slight Chance Showers And Thunderstorms 8 to 13 mph N 24%
Tuesday Night 55°F Mostly Cloudy 5 to 13 mph N 11%
Wednesday 76°F Mostly Sunny 7 to 10 mph N 2%
Wednesday Night 55°F Partly Cloudy 2 to 9 mph N 0%
Thursday 77°F Mostly Sunny 3 to 9 mph N 2%
Thursday Night 57°F Partly Cloudy 2 to 7 mph NNE 4%
Friday 78°F Mostly Sunny 3 to 9 mph NNE 4%
Friday Night 57°F Partly Cloudy 3 to 7 mph NE 2%

Forecast source: National Weather Service (api.weather.gov) for St. Johns (38.035, -89.239). Updated through the day.

Growing snapshot for St. Johns

Last spring frost
Apr 6
First fall frost
Oct 22
Growing season
199 days
Hardiness zone
7a

More local growing data for St. Johns: nearby ZIP 62832 weather · frost dates · planting calendar · Illinois frost dates

Nearby towns & communities

All Illinois locations ›

Climate data from the nearest NOAA station, Du Quoin 4 Se, Il (3.6 mi from St. Johns). Frost dates are 1991–2020 averages, not a forecast. Page updated Sep 19, 2026.