DeKalb, IL Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for DeKalb, a city in Dekalb County, Illinois.
Overnight
61°F
Mostly Clear
Mostly clear, with a low around 61. South southwest wind around 5 mph.
7-day forecast for DeKalb
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Overnight | 61°F | Mostly Clear | 5 mph SSW | 0% |
| Tuesday | 83°F | Mostly Sunny | 5 to 10 mph SSW | 0% |
| Tuesday Night | 66°F | Mostly Cloudy then Slight Chance Showers And Thunderstorms | 5 mph SW | 50% |
| 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 | 62°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 | 10 to 15 mph SW | 18% |
| Sunday Night | 68°F | Chance Showers And Thunderstorms | 5 to 10 mph SSW | 40% |
| Monday | 84°F | Chance Rain Showers | 5 to 10 mph SSW | 37% |
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 Aug 4, 2026.