Belvidere, IL Weather & Growing Conditions
Today
84°F
Mostly Sunny
Mostly sunny, with a high near 84. Southwest wind around 10 mph.
7-day forecast
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Today | 84°F | Mostly Sunny | 10 mph SW | 2% |
| Tonight | 65°F | Chance Showers And Thunderstorms | 5 mph WSW | 69% |
| Wednesday | 76°F | Showers And Thunderstorms Likely | 0 to 5 mph W | 74% |
| Wednesday Night | 60°F | Showers And Thunderstorms Likely | 0 to 5 mph ENE | 74% |
| Thursday | 78°F | Chance Rain Showers then Partly Sunny | 0 to 5 mph ENE | 39% |
| 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 | 83°F | Mostly Sunny | 0 to 10 mph SSW | 11% |
| 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 10 mph SW | 22% |
| Sunday Night | 67°F | Chance Showers And Thunderstorms | 5 to 10 mph SSW | 42% |
| Monday | 84°F | Chance Rain Showers | 5 to 10 mph SSW | 42% |
| Monday Night | 67°F | Chance Showers And Thunderstorms | 5 to 10 mph WNW | 45% |
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 Aug 4, 2026.