Last frost date in Bismarck, ND

Average last frost
May 10

The average last frost in Bismarck is May 10. By May 23 the chance of another 32°F night drops to 1 in 10. The first fall frost usually arrives about September 30, which leaves 142 frost-free days. An early freeze before September 16 happens one year in ten.

Safe after (10% risk)
May 23
Average first frost
Sep 30
Frost-free season
142 days
Hard freeze (28°F) ends
May 1
Next 7 nights in Bismarck

Frost likely Sat night, low 29°F

National Weather Service forecast, updated Oct 22, 12:57 UTC

  1. ThuOct 2256°
  2. FriOct 2344°
  3. SatOct 2429°frost
  4. SunOct 2530°frost
  5. MonOct 2629°frost
  6. TueOct 2734°possible frost
  7. WedOct 2832°frost
JanFebMarAprMayJunJulAugSepOctNovDecLast frost May 10First frost Sep 30142 frost-free daysBlue: chance of 32°F frost. Green: average frost-free season.JFMAMJJASOND142 frost-free days
Frost risk through the year at Bismarck 2.4 NNW, 1.9 miles from Bismarck.

Planting calendar for Bismarck

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

Start indoorsPlant outSow outdoorsFall plantingAverage last and first frost
Warm-season crops
JanFebMarAprMayJunJulAugSepOctNovDec
TomatoesMay 17–May 31
PumpkinsMay 24–Jun 7
SunflowersMay 10–May 31
CucumbersMay 24–May 31
CornMay 17–May 31
Sweet potatoesMay 31–Jun 14
WatermelonMay 24–Jun 7
Green beansMay 17–Jun 7
ZucchiniMay 17–May 31
OkraMay 31–Jun 14
PeppersMay 24–Jun 7
BasilMay 17–May 31
Butternut squashMay 17–May 31
CantaloupeMay 24–Jun 7
EggplantMay 24–Jun 7
Cool-season crops
JanFebMarAprMayJunJulAugSepOctNovDec
PotatoesApr 12–Apr 26
OnionsMar 29–Apr 19
CarrotsApr 19–May 24
LettuceApr 26–May 17
BroccoliApr 12–Apr 26
BeetsApr 12–May 24
PeasMar 29–Apr 12
CabbageApr 12–Apr 26
RadishesApr 5–May 17
Brussels sproutsApr 26–May 10
SpinachMar 29–Apr 19
CilantroApr 26–May 17
KaleApr 12–Apr 26
Collard greensApr 12–Apr 26
TurnipsApr 12–Apr 26
DillMay 10–May 24
CeleryMay 17–May 24
CauliflowerApr 26–May 10
LeeksApr 26–May 10
Swiss chardApr 26–May 24
ParsleyApr 26–May 17
Fall bulbs and garlic
JanFebMarAprMayJunJulAugSepOctNovDec
Tulip bulbsSep 16–Oct 21
GarlicSep 9–Oct 14
Daffodil bulbsSep 2–Oct 14
Perennials
JanFebMarAprMayJunJulAugSepOctNovDec
StrawberriesApr 12–Apr 26
AsparagusApr 12–Apr 26

Frost probabilities

ThresholdSpring, 90% chance laterSpring, 50%Spring, 10%Fall, 10% chance earlierFall, 50%Fall, 90%
Light frost, 32°FApr 30May 10May 23Sep 16Sep 30Oct 13
Hard freeze, 28°FApr 18May 1May 13Sep 25Oct 9Oct 22

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 Bismarck 2.4 NNW (USC00320817) sits 1.9 miles from the center of Bismarck at 1,831 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 Bismarck, ND?

The average last frost date in Bismarck is May 10, based on NOAA 1991–2020 climate normals. There is a 10% chance of frost after May 23.

When is the first frost in Bismarck?

The first frost in fall usually comes around September 30. One year in ten it arrives before September 16.

How long is the growing season in Bismarck?

About 142 days between the average last and first frost.

When should I plant tomatoes in Bismarck?

Plant tomato seedlings outside from May 17 to May 31. Start seeds indoors six to eight weeks earlier.

Nearby in North Dakota

All 8 cities in North Dakota