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Will it freeze in Duluth in the next 7 nights?
The earliest overnight low at or below 32°F in the available NWS frost forecast is Tonight: 29°F (Thu, Nov 5, 6:00 PM CST to Fri, Nov 6, 6:00 AM CST).
Tonight: forecast low 29°F. Freeze.
NWS forecast period: Thu, Nov 5, 6:00 PM CST to Fri, Nov 6, 6:00 AM CST.
5 of the next 7 nights are forecast at 36°F or colder, cold enough for frost on exposed plants.
- Tonight 29°F Freeze · Mostly Cloudy
- Fri, Nov 6 27°F Hard freeze · Partly Cloudy
- Sat, Nov 7 35°F Frost possible · Partly Cloudy
- Sun, Nov 8 37°F Above 36°F · Partly Cloudy
- Mon, Nov 9 38°F Above 36°F · Mostly Clear
- Tue, Nov 10 33°F Frost possible · Partly Cloudy
- Wed, Nov 11 34°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 Duluth
The median first fall hard-freeze date (28°F) is October 25, from NOAA’s 1991–2020 Climate Normals at Duluth Harbor Station. 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 | May 12 · May 31 · Jun 16 | Sep 12 · Sep 30 · Oct 14 | 121 days |
| 32°F freeze | Apr 24 · May 14 · Jun 1 | Sep 25 · Oct 12 · Oct 26 | 149 days |
| 28°F hard freeze | Apr 11 · Apr 29 · May 18 | Oct 9 · Oct 25 · Nov 7 | 179 days |
Average high temperature by month
1991–2020 normals at Duluth Harbor Station
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 Duluth, MN come from the nearest weather station with freeze statistics in NOAA’s 1991–2020 Climate Normals: Duluth Harbor Station (station USC00212246, elevation 610 ft), 2.1 mi from Duluth. 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 Duluth
| City | Distance | Last spring frost | First fall frost |
|---|---|---|---|
| Hermantown, MN | 5.6 mi | May 18 | Oct 1 |
| Superior, WI | 6.2 mi | May 6 | Oct 9 |
| Cloquet, MN | 18 mi | May 26 | Sep 23 |
| Virginia, MN | 55 mi | May 12 | Oct 1 |
| Hibbing, MN | 58 mi | Jun 5 | Sep 8 |
| Ashland, WI | 62 mi | May 20 | Oct 2 |
| Grand Rapids, MN | 73 mi | May 17 | Sep 24 |
| Rice Lake, WI | 91 mi | May 8 | Oct 2 |
| North Branch, MN | 96 mi | May 19 | Sep 25 |
| Cambridge, MN | 99 mi | May 2 | Oct 4 |
Frequently asked questions
When is the last frost in Duluth?
On average, the last spring frost (32°F) in Duluth is around May 14. In about 1 year in 10 it comes after June 1, and in 9 years in 10 it comes after April 24.
When is the first frost in Duluth?
The first fall frost (32°F) usually arrives around October 12. There’s a 10% chance of a freeze by September 25 and a 90% chance by October 26.
Can it frost in Duluth 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 31.
What growing zone is Duluth?
Duluth is in USDA Plant Hardiness Zone 4b (average annual extreme minimum temperature −25 to −20°F), based on the 2023 USDA map for ZIP code 55806. See growing zones in Minnesota.
More: all Minnesota frost dates · Minnesota growing zones · UV index today in Duluth · frost vs. freeze