Decatur, IL Weather & Growing Conditions
Today
86°F
Patchy Fog then Sunny
Patchy fog before 9am. Sunny, with a high near 86. South wind around 6 mph.
7-day forecast
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Today | 86°F | Patchy Fog then Sunny | 6 mph S | 0% |
| Tonight | 66°F | Mostly Clear | 5 mph SSE | 0% |
| Wednesday | 86°F | Mostly Sunny | 5 to 8 mph SSW | 12% |
| Wednesday Night | 67°F | Chance Showers And Thunderstorms | 7 mph S | 80% |
| Thursday | 82°F | Showers And Thunderstorms | 5 to 8 mph SSW | 80% |
| Thursday Night | 65°F | Slight Chance Showers And Thunderstorms | 2 to 6 mph S | 22% |
| Friday | 83°F | Partly Sunny | 6 mph SSW | 10% |
| Friday Night | 66°F | Slight Chance Showers And Thunderstorms | 5 mph SSW | 24% |
| Saturday | 85°F | Slight Chance Rain Showers then Mostly Sunny | 3 to 8 mph SSW | 17% |
| Saturday Night | 70°F | Mostly Clear | 6 to 9 mph S | 12% |
| Sunday | 88°F | Sunny | 9 to 14 mph SSW | 6% |
| Sunday Night | 72°F | Mostly Clear | 9 to 13 mph SSW | 11% |
| Monday | 89°F | Mostly Sunny | 13 mph SSW | 13% |
| Monday Night | 72°F | Slight Chance Showers And Thunderstorms | 12 mph SW | 25% |
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 (5.4 mi). Frost dates are 1991–2020 averages, not a forecast. Page updated Aug 4, 2026.