Decatur, IL Weather & Growing Conditions
Overnight
57°F
Light Rain
Rain. Mostly cloudy, with a low around 57. South southwest wind 14 to 17 mph, with gusts as high as 26 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 | 57°F | Light Rain | 14 to 17 mph SSW | 76% |
| Wednesday | 61°F | Mostly Cloudy | 13 to 16 mph SW | 11% |
| Wednesday Night | 46°F | Mostly Cloudy | 12 mph WSW | 6% |
| Thursday | 61°F | Mostly Cloudy | 12 to 16 mph W | 13% |
| Thursday Night | 41°F | Mostly Cloudy | 6 to 10 mph NW | 5% |
| Friday | 53°F | Partly Sunny | 14 mph NNW | 7% |
| Friday Night | 32°F | Partly Cloudy | 3 to 10 mph NNW | 0% |
| Saturday | 53°F | Sunny | 3 to 7 mph NNW | 0% |
| Saturday Night | 31°F | Partly Cloudy | 5 mph WNW | 1% |
| Sunday | 58°F | Sunny | 3 to 10 mph WNW | 1% |
| Sunday Night | 32°F | Clear | 2 to 6 mph W | 1% |
| Monday | 63°F | Sunny | 2 to 10 mph SW | 0% |
| Monday Night | 37°F | Clear | 3 to 7 mph SW | 0% |
| Tuesday | 66°F | Sunny | 6 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 (5.4 mi). Frost dates are 1991–2020 averages, not a forecast. Page updated Nov 4, 2026.