Decatur, IL Weather & Growing Conditions
This Afternoon
59°F
Patchy Drizzle
Patchy drizzle. Cloudy, with a high near 59. West southwest wind 10 to 14 mph, with gusts as high as 21 mph.
7-day forecast
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| This Afternoon | 59°F | Patchy Drizzle | 10 to 14 mph WSW | 10% |
| Tonight | 46°F | Patchy Drizzle then Mostly Cloudy | 10 mph WSW | 10% |
| Thursday | 58°F | Mostly Cloudy | 9 to 15 mph WSW | 14% |
| Thursday Night | 41°F | Slight Chance Light Rain then Mostly Cloudy | 6 to 9 mph NW | 19% |
| Friday | 51°F | Partly Sunny | 8 to 13 mph N | 2% |
| Friday Night | 31°F | Mostly Clear | 1 to 7 mph NNW | 0% |
| Saturday | 52°F | Sunny | 1 to 6 mph NNW | 0% |
| Saturday Night | 30°F | Mostly Clear | 0 to 3 mph WNW | 0% |
| Sunday | 58°F | Sunny | 1 to 8 mph W | 0% |
| Sunday Night | 33°F | Mostly Clear | 0 to 5 mph W | 0% |
| Monday | 64°F | Sunny | 0 to 8 mph SW | 0% |
| Monday Night | 38°F | Clear | 2 to 7 mph WSW | 0% |
| Tuesday | 64°F | Sunny | 2 to 6 mph WNW | 2% |
| Tuesday Night | 38°F | Mostly Clear | 3 mph NNW | 2% |
Forecast source: National Weather Service (api.weather.gov). Updated through the day.
Growing snapshot for Decatur, IL
Last spring frost
Apr 14
First fall frost
Oct 24
Growing season
192 days
Hardiness zone
6a
Explore more for Decatur, IL: full frost dates · planting calendar · Illinois frost dates
Climate data from the nearest NOAA station, Decatur Wtp, Il (1 mi). Frost dates are 1991–2020 averages, not a forecast. Page updated Nov 4, 2026.