DeKalb, IL Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for DeKalb, a city in Dekalb County, Illinois.
Tonight
62°F
Slight Chance Rain Showers then Chance Showers And Thunderstorms
A slight chance of rain showers before midnight, then a chance of showers and thunderstorms. Mostly cloudy, with a low around 62. East southeast wind around 10 mph, with gusts as high as 20 mph. Chance of precipitation is 50%. New rainfall amounts between a half and three quarters of an inch possible.
7-day forecast for DeKalb
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Tonight | 62°F | Slight Chance Rain Showers then Chance Showers And Thunderstorms | 10 mph ESE | 50% |
| Saturday | 77°F | Showers And Thunderstorms Likely | 5 to 10 mph SSE | 86% |
| Saturday Night | 63°F | Showers And Thunderstorms Likely then Showers And Thunderstorms | 5 to 10 mph NE | 80% |
| Sunday | 68°F | Showers And Thunderstorms | 10 to 15 mph NNE | 78% |
| Sunday Night | 55°F | Rain Showers Likely | 15 mph NE | 61% |
| Monday | 64°F | Chance Rain Showers | 15 mph ENE | 49% |
| Monday Night | 50°F | Chance Rain Showers | 10 to 15 mph ENE | 33% |
| Tuesday | 63°F | Chance Rain Showers | 10 to 15 mph NE | 28% |
| Tuesday Night | 49°F | Mostly Cloudy | 5 to 15 mph NE | 10% |
| Wednesday | 66°F | Partly Sunny | 5 to 10 mph NNE | 6% |
| Wednesday Night | 50°F | Partly Cloudy | 5 to 10 mph NNE | 4% |
| Thursday | 69°F | Partly Sunny | 5 to 10 mph NNE | 4% |
| Thursday Night | 51°F | Partly Cloudy | 5 mph NNE | 4% |
| Friday | 70°F | Mostly Sunny | 5 to 10 mph NNE | 5% |
Forecast source: National Weather Service (api.weather.gov) for DeKalb (41.929, -88.746). Updated through the day.
Growing snapshot for DeKalb
Last spring frost
Apr 24
First fall frost
Oct 18
Growing season
177 days
Hardiness zone
5b
More local growing data for DeKalb: nearby ZIP 60115 weather · frost dates · planting calendar · Illinois frost dates
Nearby towns & communities
Cortland
Genoa
Hinckley
Kingston
Kirkland
Lake Holiday
Malta
Sandwich
Shabbona
Somonauk
Sycamore
Waterman
Climate data from the nearest NOAA station, De Kalb, Il (2.4 mi from DeKalb). Frost dates are 1991–2020 averages, not a forecast. Page updated Sep 19, 2026.