Frost Dates for Brookfield, WI
In Brookfield, WI, the average last spring frost is around Apr 30 and the average first fall frost around Oct 14, for a growing season of about 164 days. For frost-tender plants, wait until May 15, when the chance of frost drops to 10%.
Based on NOAA 1991–2020 records from the Brookfield Wwtp, WI weather station, 3 miles away, elevation 830 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 15 | Sep 28 |
| 20% | May 8 | Oct 3 |
| 30% | May 5 | Oct 7 |
| 40% | May 2 | Oct 11 |
| 50% | Apr 30 | Oct 14 |
| 60% | Apr 28 | Oct 16 |
| 70% | Apr 25 | Oct 20 |
| 80% | Apr 21 | Oct 23 |
| 90% | Apr 16 | Oct 27 |
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 10 | Oct 3 |
| Frost / freeze (32°F) | Apr 30 | Oct 14 |
| Hard freeze (28°F) | Apr 19 | Oct 25 |
Planting calendar for Brookfield
Transplant May 7 – May 21
Transplant May 14 – May 28
Transplant May 14 – May 28
Transplant May 7 – May 21
Sow or transplant May 7 – May 21
Sow or transplant May 7 – May 21
Sow or transplant May 14 – May 28
Sow or transplant Apr 2 – Apr 16
Fall sowing Aug 19 – Sep 16
Fall sowing Aug 19 – Sep 9
Fall sowing Aug 5 – Aug 19
Sow or transplant Apr 2 – Apr 16
Fall sowing Aug 5 – Sep 2
Transplant Apr 16 – Apr 30
Fall sowing Jul 22 – Aug 5
Transplant Apr 9 – Apr 23
Fall sowing Jul 22 – Aug 5
Fall sowing Jul 22 – Aug 5
Fall sowing Sep 2 – Sep 23
Fall sowing Aug 5 – Aug 19
Plant Apr 2 – Apr 16
Based on the average last frost (Apr 30) and first frost (Oct 14). The dashed lines mark those dates. Seed packets list days to maturity; adjust for your varieties.