Frost Dates for Duluth, MN
In Duluth, MN, the average last spring frost is around May 14 and the average first fall frost around Oct 12, for a growing season of about 149 days. For frost-tender plants, wait until Jun 1, when the chance of frost drops to 10%.
Based on NOAA 1991–2020 records from the Duluth Harbor Stn, MN weather station, 2 miles away, elevation 610 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% | Jun 1 | Sep 25 |
| 20% | May 27 | Oct 1 |
| 30% | May 22 | Oct 5 |
| 40% | May 18 | Oct 9 |
| 50% | May 14 | Oct 12 |
| 60% | May 9 | Oct 15 |
| 70% | May 4 | Oct 18 |
| 80% | Apr 30 | Oct 22 |
| 90% | Apr 24 | Oct 26 |
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 31 | Sep 30 |
| Frost / freeze (32°F) | May 14 | Oct 12 |
| Hard freeze (28°F) | Apr 29 | Oct 25 |
Planting calendar for Duluth
Transplant May 21 – Jun 4
Transplant May 28 – Jun 11
Transplant May 28 – Jun 11
Transplant May 21 – Jun 4
Sow or transplant May 21 – Jun 4
Sow or transplant May 21 – Jun 4
Sow or transplant May 28 – Jun 11
Sow or transplant Apr 16 – Apr 30
Fall sowing Aug 17 – Sep 14
Fall sowing Aug 17 – Sep 7
Fall sowing Aug 3 – Aug 17
Sow or transplant Apr 16 – Apr 30
Fall sowing Aug 3 – Aug 31
Transplant Apr 30 – May 14
Fall sowing Jul 20 – Aug 3
Transplant Apr 23 – May 7
Fall sowing Jul 20 – Aug 3
Fall sowing Jul 20 – Aug 3
Fall sowing Aug 31 – Sep 21
Fall sowing Aug 3 – Aug 17
Plant Apr 16 – Apr 30
Based on the average last frost (May 14) and first frost (Oct 12). The dashed lines mark those dates. Seed packets list days to maturity; adjust for your varieties.