Decatur, IL Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for Decatur, a city in Macon County, Illinois.
Today
87°F
Mostly Sunny
Mostly sunny, with a high near 87. South wind around 6 mph.
7-day forecast for Decatur
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Today | 87°F | Mostly Sunny | 6 mph S | 0% |
| Tonight | 66°F | Mostly Clear | 5 mph SSE | 0% |
| Wednesday | 88°F | Mostly Sunny | 3 to 7 mph S | 10% |
| Wednesday Night | 68°F | Chance Showers And Thunderstorms | 3 to 7 mph S | 80% |
| Thursday | 83°F | Showers And Thunderstorms | 7 mph SSW | 80% |
| Thursday Night | 66°F | Slight Chance Showers And Thunderstorms | 2 to 6 mph SSE | 23% |
| Friday | 84°F | Partly Sunny | 5 mph SSW | 11% |
| Friday Night | 67°F | Slight Chance Showers And Thunderstorms | 3 mph SSW | 23% |
| Saturday | 86°F | Slight Chance Rain Showers then Mostly Sunny | 3 to 7 mph SSW | 18% |
| Saturday Night | 70°F | Mostly Clear | 8 mph S | 12% |
| Sunday | 89°F | Sunny | 8 to 13 mph SSW | 6% |
| Sunday Night | 72°F | Mostly Clear | 9 to 13 mph SSW | 11% |
| Monday | 90°F | Mostly Sunny | 12 mph SSW | 13% |
| Monday Night | 73°F | Slight Chance Showers And Thunderstorms | 10 mph SW | 25% |
Forecast source: National Weather Service (api.weather.gov) for Decatur (39.856, -88.934). Updated through the day.
Growing snapshot for Decatur
Last spring frost
Apr 14
First fall frost
Oct 24
Growing season
192 days
Hardiness zone
6a
More local growing data for Decatur: nearby ZIP 62523 weather · frost dates · planting calendar · Illinois frost dates
Nearby towns & communities
Argenta
Boody
Dalton City
Elwin
Forsyth
Harristown
Long Creek
Macon
Maroa
Mount Zion
Niantic
Oreana
Warrensburg
Climate data from the nearest NOAA station, Decatur Wtp, Il (1 mi from Decatur). Frost dates are 1991–2020 averages, not a forecast. Page updated Aug 4, 2026.