Frost dates for 55810Duluth, MN
The average last spring frost in Duluth is May 13 and the average first fall frost is October 1, giving a typical growing season of about 140 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 13
- Average first fall frost
- Oct 1
- Growing season
- 140 days
Safer after May 29 (1-in-10 risk)
Possible by Sep 18 (1-in-10 risk)
Last frost typically in 199 days
Frost risk by date
NOAA reports frost dates as probabilities. The middle date is the average (a 50% chance). For spring, the 10% date is a safer planting date: frost after it happens in about 1 year in 10. Light frost (36°F) can damage tender plants; a hard freeze (28°F) kills most annuals.
| Temperature | Last spring: 90% / 50% / 10% chance | First fall: 10% / 50% / 90% chance | Growing season (50%) | Years with at least one |
|---|---|---|---|---|
| Light frost (36°F) | May 11 · May 26 · Jun 9 | Sep 8 · Sep 23 · Oct 5 | 117 days | 100% |
| Frost / freeze (32°F) | Apr 29 · May 13 · May 29 | Sep 18 · Oct 1 · Oct 16 | 140 days | 100% |
| Hard freeze (28°F) | Apr 17 · Apr 30 · May 16 | Sep 29 · Oct 13 · Oct 28 | 165 days | 100% |
Planting calendar for Duluth
Planting windows from the University of Maryland Extension calendar, shifted to your average frost dates. Use them as a starting point and adjust for seed packet instructions and local conditions.
| Crop | Task | Window |
|---|---|---|
| Tomatoes | Start seeds indoors | Apr 12 – Jun 18 |
| Tomatoes | Transplant outdoors | May 29 – Jun 11 |
| Peppers | Start seeds indoors | Apr 12 – May 13 |
| Peppers | Transplant outdoors | Jun 12 – Jul 13 |
| Eggplant | Start seeds indoors | Apr 29 – May 28 |
| Eggplant | Transplant outdoors | Jun 12 – Jul 13 |
| Cucumbers | Sow outdoors | Jun 12 – Jun 21 |
| Summer squash | Sow outdoors | May 29 – Jul 13 |
| Winter squash & pumpkins | Sow outdoors | Jun 12 – Jul 13 |
| Snap beans | Sow outdoors | May 29 – Jul 14 |
| Sweet corn | Sow outdoors | May 29 – Jun 11 |
| Watermelon & cantaloupe | Sow outdoors | Jun 12 – Jul 13 |
| Okra | Sow outdoors | Jun 5 – Jun 28 |
| Peas | Sow outdoors (spring) | Apr 12 – May 28 |
| Potatoes | Plant outdoors (spring) | Apr 12 – Jun 12 |
| Onions | Start seeds indoors (spring) | Mar 1 – Mar 28 |
| Onions | Transplant outdoors (spring) | Apr 29 – May 28 |
| Broccoli | Start seeds indoors (spring) | Mar 25 – Apr 28 |
| Broccoli | Transplant outdoors (spring) | Apr 29 – May 28 |
| Broccoli | Start seeds indoors (fall) | Jun 1 – Jun 11 |
| Broccoli | Transplant outdoors (fall) | Jul 1 – Jul 12 |
| Cabbage | Start seeds indoors (spring) | Mar 15 – Apr 12 |
| Cabbage | Transplant outdoors (spring) | Apr 12 – May 13 |
| Cabbage | Start seeds indoors (fall) | May 22 – Jun 21 |
| Cabbage | Transplant outdoors (fall) | Jun 21 – Jul 22 |
| Leaf lettuce | Sow outdoors (spring) | Apr 12 – Jun 28 |
| Leaf lettuce | Sow outdoors (fall) | Jun 21 – Aug 7 |
| Spinach | Sow outdoors (spring) | Apr 5 – May 19 |
| Spinach | Sow outdoors (fall) | Jul 8 – Aug 12 |
| Radishes | Sow outdoors (spring) | Apr 12 – Jun 2 |
| Radishes | Sow outdoors (fall) | Jun 21 – Aug 22 |
| Kale | Sow outdoors (spring) | Apr 29 – May 19 |
| Kale | Sow outdoors (fall) | Jun 14 – Jul 22 |
| Carrots | Sow outdoors (spring) | May 13 – Jun 28 |
| Carrots | Sow outdoors (fall) | May 22 – Jul 7 |
| Garlic | Plant outdoors (fall) | Sep 21 – Oct 22 |
Where these dates come from
ZIP code 55810 is matched to the NOAA station Duluth, MN, 9.5 km away, at 1,428 ft elevation (142 ft higher than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Duluth, MN (used) | 1,428 ft | May 13 | Oct 1 |
| Duluth Nws, MN | 1,433 ft | May 18 | Oct 1 |
| Duluth Harbor Stn, MN | 610 ft | May 14 | Oct 12 |
| Superior, WI | 607 ft | May 6 | Oct 9 |
Frost dates near Duluth
- Duluth, MN 55807 · last May 6, first Oct 9
- Esko, MN 55733 · last May 26, first Sep 23
- Superior, WI 54880 · last May 6, first Oct 9
- Saginaw, MN 55779 · last May 13, first Oct 1
- Twig, MN 55791 · last May 13, first Oct 1
- Carlton, MN 55718 · last May 26, first Sep 23
- Wrenshall, MN 55797 · last Jun 1, first Sep 22
- Cloquet, MN 55720 · last May 26, first Sep 23
Frequently asked questions
- When is the last frost in Duluth, MN?
- For ZIP code 55810, the average last spring frost (32°F) is May 13, based on NOAA 1991-2020 climate normals for the Duluth, MN weather station. There is a 1-in-10 chance of a frost after May 29.
- When is the first frost in Duluth, MN?
- The average first fall frost (32°F) is October 1. There is a 1-in-10 chance of frost by September 18, so tender plants are at risk from that point on.
- How long is the growing season in 55810?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 140 days long.
- Are these frost dates a forecast?
- No. They are 30-year averages and probabilities from NOAA weather station records. Use them to plan, then watch your local forecast before planting tender crops or leaving them uncovered.