DeKalb, IL Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for DeKalb, a city in Dekalb County, Illinois.
Overnight
57°F
Rain
Rain. Cloudy. Low around 57, with temperatures rising to around 60 overnight. South wind around 15 mph, with gusts as high as 30 mph. Chance of precipitation is 90%. New rainfall amounts less than a tenth of an inch possible.
7-day forecast for DeKalb
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Overnight | 57°F | Rain | 15 mph S | 87% |
| Wednesday | 60°F | Chance Rain then Chance Rain Showers | 15 mph SSW | 48% |
| Wednesday Night | 46°F | Slight Chance Rain Showers | 15 mph SW | 19% |
| Thursday | 55°F | Chance Rain Showers | 10 to 15 mph WSW | 38% |
| Thursday Night | 41°F | Chance Rain Showers | 5 to 10 mph NW | 40% |
| Friday | 51°F | Slight Chance Rain Showers then Mostly Cloudy | 10 mph N | 20% |
| Friday Night | 34°F | Partly Cloudy | 5 to 10 mph NNW | 3% |
| Saturday | 51°F | Mostly Sunny | 5 mph WNW | 2% |
| Saturday Night | 34°F | Partly Cloudy | 0 to 5 mph WSW | 4% |
| Sunday | 57°F | Mostly Sunny | 5 to 10 mph W | 13% |
| Sunday Night | 35°F | Mostly Clear | 5 mph W | 5% |
| Monday | 60°F | Sunny | 5 to 15 mph WSW | 3% |
| Monday Night | 39°F | Mostly Clear | 5 to 10 mph W | 1% |
| Tuesday | 61°F | Sunny | 5 to 10 mph WNW | 1% |
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 Nov 4, 2026.