Belvidere, IL Weather & Growing Conditions
Tonight
57°F
Rain
Rain. Cloudy. Low around 57, with temperatures rising to around 60 overnight. South southeast wind around 15 mph, with gusts as high as 30 mph. Chance of precipitation is 90%. New rainfall amounts between a quarter and half of an inch possible.
7-day forecast
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Tonight | 57°F | Rain | 15 mph SSE | 87% |
| Wednesday | 61°F | Chance Rain then Chance Rain Showers | 15 mph SSW | 51% |
| Wednesday Night | 46°F | Chance Rain Showers | 15 mph SW | 32% |
| Thursday | 55°F | Chance Rain Showers | 10 to 15 mph WSW | 49% |
| Thursday Night | 40°F | Chance Rain Showers | 5 to 10 mph NW | 37% |
| Friday | 50°F | Slight Chance Rain Showers then Mostly Cloudy | 10 mph N | 19% |
| Friday Night | 32°F | Partly Cloudy | 0 to 5 mph NNW | 3% |
| Saturday | 51°F | Mostly Sunny | 0 to 5 mph WNW | 2% |
| Saturday Night | 32°F | Partly Cloudy | 0 to 5 mph WSW | 4% |
| Sunday | 57°F | Mostly Sunny then Slight Chance Rain | 5 to 10 mph W | 16% |
| Sunday Night | 33°F | Mostly Clear | 0 to 5 mph W | 5% |
| Monday | 61°F | Sunny | 5 to 10 mph WSW | 2% |
| Monday Night | 38°F | Mostly Clear | 5 to 10 mph W | 1% |
| Tuesday | 61°F | Mostly Sunny | 5 to 10 mph WNW | 1% |
Forecast source: National Weather Service (api.weather.gov). Updated through the day.
Growing snapshot for Belvidere, IL
Last spring frost
Apr 28
First fall frost
Oct 12
Growing season
166 days
Hardiness zone
5b
Explore more for Belvidere, IL: full frost dates · planting calendar · Illinois frost dates
Climate data from the nearest NOAA station, Marengo, Il (11.9 mi). Frost dates are 1991–2020 averages, not a forecast. Page updated Nov 4, 2026.