Belvidere, IL Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for Belvidere, a city in Boone County, Illinois.
Overnight
61°F
Mostly Clear
Mostly clear, with a low around 61. South wind around 5 mph.
7-day forecast for Belvidere
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Overnight | 61°F | Mostly Clear | 5 mph S | 0% |
| Tuesday | 84°F | Mostly Sunny | 5 to 10 mph SSW | 3% |
| Tuesday Night | 65°F | Chance Showers And Thunderstorms | 0 to 5 mph SW | 71% |
| Wednesday | 77°F | Showers And Thunderstorms Likely | 0 to 5 mph WNW | 74% |
| Wednesday Night | 60°F | Showers And Thunderstorms Likely | 0 to 5 mph NNW | 73% |
| Thursday | 79°F | Chance Rain Showers then Partly Sunny | 0 to 5 mph NE | 37% |
| Thursday Night | 58°F | Partly Cloudy | 0 mph | 14% |
| Friday | 81°F | Mostly Sunny | 0 to 5 mph SSE | 6% |
| Friday Night | 61°F | Mostly Clear | 0 to 5 mph S | 7% |
| Saturday | 84°F | Mostly Sunny | 0 to 10 mph SSW | 10% |
| Saturday Night | 67°F | Partly Cloudy then Slight Chance Showers And Thunderstorms | 5 mph SSW | 22% |
| Sunday | 85°F | Slight Chance Showers And Thunderstorms | 5 to 15 mph SW | 22% |
| Sunday Night | 67°F | Chance Showers And Thunderstorms | 5 to 10 mph SSW | 43% |
| Monday | 84°F | Chance Rain Showers | 5 to 10 mph SSW | 42% |
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 Aug 4, 2026.