Belvidere, IL Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for Belvidere, a city in Boone County, Illinois.
This Afternoon
72°F
Slight Chance Rain Showers
A slight chance of rain showers. Mostly cloudy, with a high near 72. East wind around 15 mph, with gusts as high as 25 mph. Chance of precipitation is 20%. New rainfall amounts less than a tenth of an inch possible.
7-day forecast for Belvidere
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| This Afternoon | 72°F | Slight Chance Rain Showers | 15 mph E | 22% |
| Tonight | 61°F | Slight Chance Rain Showers then Showers And Thunderstorms Likely | 10 mph E | 67% |
| Saturday | 76°F | Showers And Thunderstorms then Showers And Thunderstorms Likely | 5 to 10 mph ESE | 93% |
| Saturday Night | 62°F | Showers And Thunderstorms Likely then Showers And Thunderstorms | 5 to 10 mph NE | 77% |
| Sunday | 67°F | Showers And Thunderstorms Likely | 10 to 15 mph NE | 69% |
| Sunday Night | 53°F | Chance Rain Showers | 15 mph NE | 48% |
| Monday | 64°F | Chance Rain Showers | 15 mph ENE | 39% |
| Monday Night | 48°F | Chance Rain Showers | 10 to 15 mph NE | 39% |
| Tuesday | 63°F | Chance Rain Showers | 10 to 15 mph NE | 28% |
| Tuesday Night | 47°F | Mostly Cloudy | 5 to 10 mph NE | 11% |
| Wednesday | 66°F | Partly Sunny | 5 to 10 mph NE | 5% |
| Wednesday Night | 48°F | Partly Cloudy | 0 to 10 mph NNE | 4% |
| Thursday | 68°F | Partly Sunny | 0 to 5 mph NNE | 4% |
| Thursday Night | 49°F | Mostly Cloudy | 0 to 5 mph NE | 4% |
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 Sep 19, 2026.