Decatur, IL Weather & Growing Conditions
Overnight
69°F
Partly Cloudy
Partly cloudy, with a low around 69. South southeast wind around 7 mph.
7-day forecast
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Overnight | 69°F | Partly Cloudy | 7 mph SSE | 11% |
| Saturday | 90°F | Slight Chance Showers And Thunderstorms | 8 mph SSW | 17% |
| Saturday Night | 69°F | Partly Cloudy then Slight Chance Showers And Thunderstorms | 6 mph SSW | 19% |
| Sunday | 84°F | Chance Showers And Thunderstorms | 3 to 12 mph N | 48% |
| Sunday Night | 61°F | Chance Showers And Thunderstorms | 14 mph NE | 61% |
| Monday | 70°F | Showers And Thunderstorms Likely | 16 mph NE | 70% |
| Monday Night | 55°F | Chance Rain Showers | 14 mph NE | 48% |
| Tuesday | 68°F | Slight Chance Rain Showers then Slight Chance Showers And Thunderstorms | 15 mph NE | 21% |
| Tuesday Night | 52°F | Slight Chance Showers And Thunderstorms then Mostly Cloudy | 7 to 13 mph NNE | 18% |
| Wednesday | 71°F | Mostly Sunny | 12 mph NNE | 3% |
| Wednesday Night | 54°F | Partly Cloudy | 5 to 10 mph NNE | 2% |
| Thursday | 73°F | Mostly Sunny | 6 to 9 mph NNE | 3% |
| Thursday Night | 55°F | Partly Cloudy | 5 to 8 mph NNE | 3% |
| Friday | 75°F | Mostly Sunny | 6 to 10 mph NE | 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 Sep 19, 2026.