DeKalb, IL Weather & Growing Conditions
Today
83°F
Mostly Sunny
Mostly sunny, with a high near 83. South southwest wind 5 to 10 mph.
7-day forecast
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Today | 83°F | Mostly Sunny | 5 to 10 mph SSW | 1% |
| Tonight | 66°F | Mostly Cloudy then Slight Chance Showers And Thunderstorms | 5 to 10 mph SW | 48% |
| Wednesday | 77°F | Showers And Thunderstorms Likely | 5 mph WSW | 74% |
| Wednesday Night | 62°F | Showers And Thunderstorms | 0 to 5 mph NNW | 83% |
| Thursday | 78°F | Rain Showers Likely then Slight Chance Showers And Thunderstorms | 0 to 5 mph NE | 55% |
| Thursday Night | 60°F | Slight Chance Showers And Thunderstorms then Partly Cloudy | 0 to 5 mph SE | 19% |
| Friday | 81°F | Mostly Sunny | 0 to 5 mph SSE | 8% |
| Friday Night | 63°F | Mostly Clear | 0 to 5 mph SSW | 9% |
| Saturday | 83°F | Mostly Sunny | 5 to 10 mph SSW | 9% |
| Saturday Night | 68°F | Partly Cloudy then Slight Chance Showers And Thunderstorms | 5 to 10 mph SSW | 18% |
| Sunday | 85°F | Slight Chance Showers And Thunderstorms then Mostly Sunny | 10 to 15 mph SW | 18% |
| Sunday Night | 68°F | Chance Showers And Thunderstorms | 5 to 10 mph SSW | 39% |
| Monday | 84°F | Chance Rain Showers | 5 to 10 mph SSW | 37% |
| Monday Night | 68°F | Chance Showers And Thunderstorms | 10 mph W | 44% |
Forecast source: National Weather Service (api.weather.gov). Updated through the day.
Growing snapshot for DeKalb, IL
Last spring frost
Apr 24
First fall frost
Oct 18
Growing season
177 days
Hardiness zone
5b
Explore more for DeKalb, IL: full frost dates · planting calendar · Illinois frost dates
Climate data from the nearest NOAA station, De Kalb, Il (2.4 mi). Frost dates are 1991–2020 averages, not a forecast. Page updated Aug 4, 2026.