Decatur, IL Weather & Growing Conditions
Overnight
54°F
Rain
Rain before 4am, then a slight chance of rain showers. Mostly cloudy. Low around 54, with temperatures rising to around 59 overnight. South southwest wind around 17 mph, with gusts as high as 22 mph. Chance of precipitation is 80%. New rainfall amounts between a tenth and quarter of an inch possible.
7-day forecast
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Overnight | 54°F | Rain | 17 mph SSW | 83% |
| Wednesday | 60°F | Slight Chance Rain Showers then Mostly Cloudy | 12 to 15 mph SW | 17% |
| Wednesday Night | 44°F | Mostly Cloudy | 10 mph SW | 1% |
| Thursday | 61°F | Mostly Sunny | 9 to 15 mph WSW | 4% |
| Thursday Night | 43°F | Mostly Cloudy then Slight Chance Light Rain | 3 to 7 mph WNW | 21% |
| Friday | 55°F | Mostly Cloudy | 6 to 12 mph NNW | 13% |
| Friday Night | 36°F | Mostly Cloudy | 2 to 9 mph NNW | 7% |
| Saturday | 53°F | Mostly Sunny | 5 mph NW | 1% |
| Saturday Night | 34°F | Partly Cloudy | 3 mph W | 2% |
| Sunday | 59°F | Sunny | 2 to 9 mph W | 9% |
| Sunday Night | 34°F | Mostly Clear | 3 to 7 mph WNW | 6% |
| Monday | 63°F | Sunny | 3 to 12 mph WSW | 3% |
| Monday Night | 39°F | Mostly Clear | 5 to 8 mph WSW | 2% |
| Tuesday | 66°F | Sunny | 7 mph WNW | 1% |
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.