Checking current alerts… View NWS forecast and alerts.
Will it freeze in Belvidere in the next 7 nights?
The earliest overnight low at or below 32°F in the available NWS frost forecast is Fri, Nov 6: 26°F (Fri, Nov 6, 6:00 PM CST to Sat, Nov 7, 6:00 AM CST).
Tonight: forecast low 35°F. Frost possible.
NWS forecast period: Thu, Nov 5, 6:00 PM CST to Fri, Nov 6, 6:00 AM CST.
6 of the next 7 nights are forecast at 36°F or colder, cold enough for frost on exposed plants.
- Tonight 35°F Frost possible · Patchy Drizzle then Mostly Cloudy
- Fri, Nov 6 26°F Hard freeze · Mostly Clear
- Sat, Nov 7 31°F Freeze · Partly Cloudy
- Sun, Nov 8 32°F Freeze · Mostly Clear
- Mon, Nov 9 38°F Above 36°F · Mostly Clear
- Tue, Nov 10 36°F Frost possible · Partly Cloudy
- Wed, Nov 11 36°F Frost possible · Partly Cloudy
Overnight lows from the National Weather Service forecast for this location. This covers the available forecast window, not the first freeze of the whole season. Frost can form above 32°F on clear, calm nights.
Frost and freeze probabilities
Freeze dates shift from year to year. Spring percentages describe the chance of a freeze after the stated date; fall percentages describe the chance of a freeze by that date. The 10% spring date is the cautious one: a later freeze happens about 1 year in 10.
These dates describe historical probabilities, not this year’s forecast or the earliest and latest possible freezes. Different weather stations or probability thresholds can produce different published dates for the same city.
Average first hard freeze in Belvidere
The median first fall hard-freeze date (28°F) is October 28, from NOAA’s 1991–2020 Climate Normals at Rockford Gtr Rockford Airport. This is the 50% probability date, not a forecast for this year.
| Temperature | Last spring date 90% · 50% · 10% chance of a later freeze | First fall date 10% · 50% · 90% chance of an earlier freeze | Season |
|---|---|---|---|
| 36°F frost possible | Apr 21 · May 4 · May 19 | Sep 23 · Oct 6 · Oct 20 | 153 days |
| 32°F freeze | Apr 10 · Apr 24 · May 8 | Oct 2 · Oct 17 · Oct 30 | 174 days |
| 28°F hard freeze | Mar 31 · Apr 13 · Apr 27 | Oct 14 · Oct 28 · Nov 10 | 197 days |
Average high temperature by month
1991–2020 normals at Rockford Gtr Rockford Airport
Average low temperature by month
Months with lows near or below freezing carry frost risk
Where these frost dates come from
The frost dates for Belvidere, IL come from the nearest weather station with freeze statistics in NOAA’s 1991–2020 Climate Normals: Rockford Gtr Rockford Airport (station USW00094822, elevation 730 ft), 12 mi from Belvidere. Local conditions (valleys, hilltops, distance to water, city heat) can shift frost dates by days or weeks. The hardiness zone is from the 2023 USDA Plant Hardiness Zone Map (USDA ARS and Oregon State University PRISM). See our methodology.
Frost dates near Belvidere
| City | Distance | Last spring frost | First fall frost |
|---|---|---|---|
| Poplar Grove, IL | 6.2 mi | Apr 28 | Oct 12 |
| Loves Park, IL | 7.5 mi | Apr 24 | Oct 17 |
| Rockford, IL | 8.7 mi | Apr 24 | Oct 17 |
| Machesney Park, IL | 9.9 mi | May 1 | Oct 12 |
| Roscoe, IL | 12 mi | May 1 | Oct 12 |
| Marengo, IL | 15 mi | Apr 28 | Oct 12 |
| Rockton, IL | 16 mi | May 1 | Oct 12 |
| Genoa, IL | 16 mi | Apr 24 | Oct 18 |
| South Beloit, IL | 17 mi | May 1 | Oct 12 |
| Harvard, IL | 18 mi | Apr 28 | Oct 12 |
Frequently asked questions
When is the last frost in Belvidere?
On average, the last spring frost (32°F) in Belvidere is around April 24. In about 1 year in 10 it comes after May 8, and in 9 years in 10 it comes after April 10.
When is the first frost in Belvidere?
The first fall frost (32°F) usually arrives around October 17. There’s a 10% chance of a freeze by October 2 and a 90% chance by October 30.
Can it frost in Belvidere after the last frost date?
Yes. Frost can form on clear, calm nights even when the air stays above 32°F. Temperatures of 36°F or lower, cold enough for frost on exposed plants, have a 50% chance of occurring after May 4.
What growing zone is Belvidere?
Belvidere is in USDA Plant Hardiness Zone 5b (average annual extreme minimum temperature −15 to −10°F), based on the 2023 USDA map for ZIP code 61008. See growing zones in Illinois.
More: all Illinois frost dates · Illinois growing zones · UV index today in Belvidere · frost vs. freeze