National Weather Service Forecast for: De Kalb IL
Issued by: National Weather Service Chicago, IL
Updated: 12:21 am CST Dec 18, 2025
 
Overnight

Overnight: A 50 percent chance of showers, mainly after 4am. Mostly cloudy, with a temperature rising to around 40 by 5am. Breezy, with a south wind 15 to 20 mph, with gusts as high as 30 mph.
Chance
Showers and
Breezy

 Thursday

Thursday: Rain showers before 4pm, then a slight chance of snow showers after 5pm. Temperature rising to near 45 by 9am, then falling to around 29 during the remainder of the day. Breezy, with a south wind 15 to 25 mph becoming west northwest in the afternoon. Winds could gust as high as 35 mph. Chance of precipitation is 100%. New snow accumulation of less than a half inch possible.
Breezy.
Showers then
Chance
Rain/Snow
 Thursday
Night
Thursday Night: Scattered snow showers, mainly before 9pm, then a chance of flurries after midnight. Mostly cloudy, with a low around 10. Wind chill values as low as -9. Breezy, with a west wind 20 to 25 mph, with gusts as high as 40 mph. Chance of precipitation is 40%.
Breezy.
Scattered
Snow Showers
then Chance
Flurries
 Friday

Friday: Mostly sunny, with a high near 26. Wind chill values as low as -9. Blustery, with a west northwest wind 15 to 20 mph becoming west southwest 10 to 15 mph in the afternoon. Winds could gust as high as 35 mph.
Mostly Sunny
and Blustery
then Mostly
Sunny
 Friday
Night
Friday Night: Mostly cloudy, with a low around 20. South wind 10 to 15 mph, with gusts as high as 25 mph.
Mostly Cloudy


 Saturday

Saturday: Mostly cloudy, with a high near 41.
Mostly Cloudy


 Saturday
Night
Saturday Night: Partly cloudy, with a low around 15.
Partly Cloudy


 Sunday

Sunday: Sunny, with a high near 29.
Sunny


 Sunday
Night
Sunday Night: Mostly cloudy, with a low around 19.
Mostly Cloudy
Lo 35 °F⇑ Hi 45 °F⇓ Lo 10 °F Hi 26 °F Lo 20 °F Hi 41 °F Lo 15 °F Hi 29 °F Lo 19 °F

 

Overnight
 
 A 50 percent chance of showers, mainly after 4am. Mostly cloudy, with a temperature rising to around 40 by 5am. Breezy, with a south wind 15 to 20 mph, with gusts as high as 30 mph.
Thursday
 
 Rain showers before 4pm, then a slight chance of snow showers after 5pm. Temperature rising to near 45 by 9am, then falling to around 29 during the remainder of the day. Breezy, with a south wind 15 to 25 mph becoming west northwest in the afternoon. Winds could gust as high as 35 mph. Chance of precipitation is 100%. New snow accumulation of less than a half inch possible.
Thursday Night
 
 Scattered snow showers, mainly before 9pm, then a chance of flurries after midnight. Mostly cloudy, with a low around 10. Wind chill values as low as -9. Breezy, with a west wind 20 to 25 mph, with gusts as high as 40 mph. Chance of precipitation is 40%.
Friday
 
 Mostly sunny, with a high near 26. Wind chill values as low as -9. Blustery, with a west northwest wind 15 to 20 mph becoming west southwest 10 to 15 mph in the afternoon. Winds could gust as high as 35 mph.
Friday Night
 
 Mostly cloudy, with a low around 20. South wind 10 to 15 mph, with gusts as high as 25 mph.
Saturday
 
 Mostly cloudy, with a high near 41.
Saturday Night
 
 Partly cloudy, with a low around 15.
Sunday
 
 Sunny, with a high near 29.
Sunday Night
 
 Mostly cloudy, with a low around 19.
Monday
 
 Mostly cloudy, with a high near 37.
Monday Night
 
 Mostly cloudy, with a low around 31.
Tuesday
 
 Partly sunny, with a high near 44.
Tuesday Night
 
 Mostly cloudy, with a low around 26.
Wednesday
 
 Partly sunny, with a high near 40.

 

Forecast from NOAA-NWS for De Kalb IL.