Last frost date in Duluth, MN

Average last frost
May 14

Expect the last frost in Duluth around May 14. Frost after June 1 happens in only one year out of ten. The first fall frost usually arrives about October 12, which leaves 149 frost-free days. An early freeze before September 25 happens one year in ten.

Safe after (10% risk)
Jun 1
Average first frost
Oct 12
Frost-free season
149 days
Hard freeze (28°F) ends
Apr 29
Next 7 nights in Duluth

Frost possible in low spots Mon night, low 36°F

National Weather Service forecast, updated Oct 22, 12:24 UTC

  1. ThuOct 2246°
  2. FriOct 2356°
  3. SatOct 2444°
  4. SunOct 2540°
  5. MonOct 2636°possible frost
  6. TueOct 2737°
  7. WedOct 2840°
JanFebMarAprMayJunJulAugSepOctNovDecLast frost May 14First frost Oct 12149 frost-free daysBlue: chance of 32°F frost. Green: average frost-free season.JFMAMJJASOND149 frost-free days
Frost risk through the year at Duluth Harbor Station, 2.1 miles from Duluth.

Planting calendar for Duluth

Windows count forward or back from the average frost dates above. Click a crop for dates across Minnesota.

Start indoorsPlant outSow outdoorsFall plantingAverage last and first frost
Warm-season crops
JanFebMarAprMayJunJulAugSepOctNovDec
TomatoesMay 21–Jun 4
PumpkinsMay 28–Jun 11
SunflowersMay 14–Jun 4
CucumbersMay 28–Jun 4
CornMay 21–Jun 4
Sweet potatoesJun 4–Jun 18
WatermelonMay 28–Jun 11
Green beansMay 21–Jun 11
ZucchiniMay 21–Jun 4
OkraJun 4–Jun 18
PeppersMay 28–Jun 11
BasilMay 21–Jun 4
Butternut squashMay 21–Jun 4
CantaloupeMay 28–Jun 11
EggplantMay 28–Jun 11
Cool-season crops
JanFebMarAprMayJunJulAugSepOctNovDec
PotatoesApr 16–Apr 30
OnionsApr 2–Apr 23
CarrotsApr 23–May 28
LettuceApr 30–May 21
BroccoliApr 16–Apr 30
BeetsApr 16–May 28
PeasApr 2–Apr 16
CabbageApr 16–Apr 30
RadishesApr 9–May 21
Brussels sproutsApr 30–May 14
SpinachApr 2–Apr 23
CilantroApr 30–May 21
KaleApr 16–Apr 30
Collard greensApr 16–Apr 30
TurnipsApr 16–Apr 30
DillMay 14–May 28
CeleryMay 21–May 28
CauliflowerApr 30–May 14
LeeksApr 30–May 14
Swiss chardApr 30–May 28
ParsleyApr 30–May 21
Fall bulbs and garlic
JanFebMarAprMayJunJulAugSepOctNovDec
Tulip bulbsSep 28–Nov 2
GarlicSep 21–Oct 26
Daffodil bulbsSep 14–Oct 26
Perennials
JanFebMarAprMayJunJulAugSepOctNovDec
StrawberriesApr 16–Apr 30
AsparagusApr 16–Apr 30

Frost probabilities

ThresholdSpring, 90% chance laterSpring, 50%Spring, 10%Fall, 10% chance earlierFall, 50%Fall, 90%
Light frost, 32°FApr 24May 14Jun 1Sep 25Oct 12Oct 26
Hard freeze, 28°FApr 11Apr 29May 18Oct 9Oct 25Nov 7

Read the spring 10% column as the date after which only one year in ten still gets frost. That is the safer date for tomatoes, peppers and basil.

Where these numbers come from

NOAA station Duluth Harbor Station (USC00212246) sits 2.1 miles from the center of Duluth at 610 feet. Its averages cover 1991 to 2020. Low spots, valleys and open fields can keep getting frost a week or two after the station stops; city centers and lakeshores usually get less of it.

Questions

When is the last frost in Duluth, MN?

The average last frost date in Duluth is May 14, based on NOAA 1991–2020 climate normals. There is a 10% chance of frost after June 1.

When is the first frost in Duluth?

The first frost in fall usually comes around October 12. One year in ten it arrives before September 25.

How long is the growing season in Duluth?

About 149 days between the average last and first frost.

When should I plant tomatoes in Duluth?

Plant tomato seedlings outside from May 21 to June 4. Start seeds indoors six to eight weeks earlier.

Nearby in Minnesota

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