DeKalb, IL Weather & Growing Conditions
Tonight
62°F
Mostly Cloudy then Chance Showers And Thunderstorms
A chance of showers and thunderstorms after midnight. Mostly cloudy, with a low around 62. East southeast wind 10 to 15 mph. Chance of precipitation is 50%. New rainfall amounts between a half and three quarters of an inch possible.
7-day forecast
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Tonight | 62°F | Mostly Cloudy then Chance Showers And Thunderstorms | 10 to 15 mph ESE | 54% |
| Saturday | 77°F | Showers And Thunderstorms Likely | 5 to 15 mph SE | 88% |
| Saturday Night | 63°F | Showers And Thunderstorms Likely then Showers And Thunderstorms | 5 to 10 mph E | 79% |
| Sunday | 68°F | Showers And Thunderstorms | 10 to 20 mph NE | 77% |
| Sunday Night | 54°F | Rain Showers Likely | 15 mph NE | 59% |
| Monday | 64°F | Chance Rain Showers | 15 to 20 mph ENE | 47% |
| Monday Night | 50°F | Chance Rain Showers | 10 to 15 mph ENE | 35% |
| Tuesday | 63°F | Chance Rain Showers | 10 to 15 mph NE | 30% |
| Tuesday Night | 48°F | Mostly Cloudy | 5 to 15 mph NE | 10% |
| Wednesday | 66°F | Partly Sunny | 5 to 10 mph NNE | 5% |
| Wednesday Night | 49°F | Partly Cloudy | 5 to 10 mph NNE | 4% |
| Thursday | 69°F | Partly Sunny | 5 to 10 mph NNE | 4% |
| Thursday Night | 50°F | Partly Cloudy | 0 to 5 mph NE | 4% |
| Friday | 70°F | Mostly Sunny | 0 to 10 mph NNE | 5% |
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 (6.1 mi). Frost dates are 1991–2020 averages, not a forecast. Page updated Sep 19, 2026.