Belvidere, IL Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for Belvidere, a city in Boone County, Illinois.
Tonight
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 between a quarter and half of an inch possible.
7-day forecast for Belvidere
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Tonight | 57°F | Rain | 15 mph S | 86% |
| Wednesday | 61°F | Chance Rain then Chance Rain Showers | 15 mph SSW | 50% |
| Wednesday Night | 46°F | Chance Rain Showers | 15 mph SW | 31% |
| Thursday | 55°F | Chance Rain Showers | 10 to 15 mph WSW | 51% |
| Thursday Night | 40°F | Chance Rain Showers | 5 to 10 mph NW | 34% |
| Friday | 51°F | Slight Chance Rain Showers then Mostly Cloudy | 10 mph N | 19% |
| Friday Night | 31°F | Partly Cloudy | 0 to 5 mph NNW | 2% |
| Saturday | 52°F | Mostly Sunny | 0 to 5 mph WNW | 2% |
| Saturday Night | 32°F | Partly Cloudy | 0 to 5 mph WSW | 3% |
| 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 15 mph WSW | 2% |
| Monday Night | 37°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 Belvidere (42.265, -88.888). Updated through the day.
Growing snapshot for Belvidere
Last spring frost
Apr 28
First fall frost
Oct 12
Growing season
166 days
Hardiness zone
5b
More local growing data for Belvidere: nearby ZIP 61008 weather · frost dates · planting calendar · Illinois frost dates
Nearby towns & communities
Climate data from the nearest NOAA station, Marengo, Il (11.9 mi from Belvidere). Frost dates are 1991–2020 averages, not a forecast. Page updated Nov 4, 2026.