Harrisburg, IL Weather & Growing Conditions
Tonight
71°F
Partly Cloudy
Partly cloudy. Low around 71, with temperatures rising to around 73 overnight. Southeast wind around 1 mph.
7-day forecast
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Tonight | 71°F | Partly Cloudy | 1 mph SE | 12% |
| Saturday | 99°F | Sunny | 1 to 8 mph SW | 2% |
| Saturday Night | 73°F | Mostly Clear | 5 mph SSW | 1% |
| Sunday | 98°F | Sunny | 3 to 7 mph WSW | 6% |
| Sunday Night | 70°F | Partly Cloudy | 3 mph N | 8% |
| Monday | 89°F | Partly Sunny then Chance Showers And Thunderstorms | 1 to 9 mph NNE | 38% |
| Monday Night | 62°F | Chance Showers And Thunderstorms | 5 to 9 mph NNE | 40% |
| Tuesday | 78°F | Chance Showers And Thunderstorms | 6 to 10 mph N | 26% |
| Tuesday Night | 57°F | Mostly Cloudy | 3 to 10 mph N | 8% |
| Wednesday | 77°F | Mostly Sunny | 5 to 9 mph N | 4% |
| Wednesday Night | 56°F | Partly Cloudy | 2 to 8 mph NNE | 4% |
| Thursday | 77°F | Mostly Sunny | 2 to 8 mph N | 3% |
| Thursday Night | 58°F | Partly Cloudy | 2 to 7 mph NNE | 3% |
| Friday | 77°F | Mostly Sunny | 2 to 9 mph NNE | 4% |
Forecast source: National Weather Service (api.weather.gov). Updated through the day.
Growing snapshot for Harrisburg, IL
Last spring frost
Apr 7
First fall frost
Oct 26
Growing season
202 days
Hardiness zone
7a
Explore more for Harrisburg, IL: full frost dates · planting calendar · Illinois frost dates
Climate data from the nearest NOAA station, Harrisburg, Il (2.8 mi). Frost dates are 1991–2020 averages, not a forecast. Page updated Sep 19, 2026.