Frost Dates for Belvidere, IL
In Belvidere, IL, the average last spring frost is around Apr 24 and the average first fall frost around Oct 17, for a growing season of about 174 days. For frost-tender plants, wait until May 8, when the chance of frost drops to 10%.
Based on NOAA 1991–2020 records from the Rockford Gtr Rockford Airport, IL weather station, 12 miles away, elevation 730 ft. Frost can come earlier in low spots and valleys and later near cities and large lakes.
Frost probability by date
Chance of a 32°F frost after the spring date, or before the fall date.
| Chance | Last spring frost | First fall frost |
|---|---|---|
| 10% | May 8 | Oct 2 |
| 20% | May 2 | Oct 8 |
| 30% | Apr 30 | Oct 12 |
| 40% | Apr 27 | Oct 14 |
| 50% | Apr 24 | Oct 17 |
| 60% | Apr 21 | Oct 19 |
| 70% | Apr 18 | Oct 22 |
| 80% | Apr 15 | Oct 26 |
| 90% | Apr 10 | Oct 30 |
Light frost vs. hard freeze
Average (50%) dates for each temperature. Tender plants are damaged at 36°F; most hardy crops survive until 28°F.
| Temperature | Last in spring | First in fall |
|---|---|---|
| Light frost (36°F) | May 4 | Oct 6 |
| Frost / freeze (32°F) | Apr 24 | Oct 17 |
| Hard freeze (28°F) | Apr 13 | Oct 28 |
Planting calendar for Belvidere
Transplant May 1 – May 15
Transplant May 8 – May 22
Transplant May 8 – May 22
Transplant May 1 – May 15
Sow or transplant May 1 – May 15
Sow or transplant May 1 – May 15
Sow or transplant May 8 – May 22
Sow or transplant Mar 27 – Apr 10
Fall sowing Aug 22 – Sep 19
Fall sowing Aug 22 – Sep 12
Fall sowing Aug 8 – Aug 22
Sow or transplant Mar 27 – Apr 10
Fall sowing Aug 8 – Sep 5
Transplant Apr 10 – Apr 24
Fall sowing Jul 25 – Aug 8
Transplant Apr 3 – Apr 17
Fall sowing Jul 25 – Aug 8
Fall sowing Jul 25 – Aug 8
Fall sowing Sep 5 – Sep 26
Fall sowing Aug 8 – Aug 22
Plant Mar 27 – Apr 10
Based on the average last frost (Apr 24) and first frost (Oct 17). The dashed lines mark those dates. Seed packets list days to maturity; adjust for your varieties.