Last frost date in Williston, ND
In Williston, the last spring frost comes around May 21 in an average year. Wait until June 3 if you want 90% odds of no more frost. The first fall frost usually arrives about September 21, which leaves 123 frost-free days. An early freeze before September 9 happens one year in ten.
- Safe after (10% risk)
- Jun 3
- Average first frost
- Sep 21
- Frost-free season
- 123 days
- Hard freeze (28°F) ends
- May 11
Hard freeze likely Sat night, low 25°F
National Weather Service forecast, updated Oct 22, 12:24 UTC
- ThuOct 2248°
- FriOct 2336°possible frost
- SatOct 2425°hard freeze
- SunOct 2527°hard freeze
- MonOct 2626°hard freeze
- TueOct 2730°frost
- WedOct 2827°hard freeze
Planting calendar for Williston
Windows count forward or back from the average frost dates above. Click a crop for dates across North Dakota.
TomatoesMay 28–Jun 11
PumpkinsJun 4–Jun 18
SunflowersMay 21–Jun 11
CucumbersJun 4–Jun 11
CornMay 28–Jun 11
Sweet potatoesJun 11–Jun 25
WatermelonJun 4–Jun 18
Green beansMay 28–Jun 18
ZucchiniMay 28–Jun 11
OkraJun 11–Jun 25
PeppersJun 4–Jun 18
BasilMay 28–Jun 11
Butternut squashMay 28–Jun 11
CantaloupeJun 4–Jun 18
EggplantJun 4–Jun 18
PotatoesApr 23–May 7
OnionsApr 9–Apr 30
CarrotsApr 30–Jun 4
LettuceMay 7–May 28
BroccoliApr 23–May 7
BeetsApr 23–Jun 4
PeasApr 9–Apr 23
CabbageApr 23–May 7
RadishesApr 16–May 28
Brussels sproutsMay 7–May 21
SpinachApr 9–Apr 30
CilantroMay 7–May 28
KaleApr 23–May 7
Collard greensApr 23–May 7
TurnipsApr 23–May 7
DillMay 21–Jun 4
CeleryMay 28–Jun 4
CauliflowerMay 7–May 21
LeeksMay 7–May 21
Swiss chardMay 7–Jun 4
ParsleyMay 7–May 28
Tulip bulbsSep 7–Oct 12
GarlicAug 31–Oct 5
Daffodil bulbsAug 24–Oct 5
StrawberriesApr 23–May 7
AsparagusApr 23–May 7The frost-free season here is short for pumpkins, sweet potatoes, butternut squash. Start them indoors and look for early varieties.
Frost probabilities
| Threshold | Spring, 90% chance later | Spring, 50% | Spring, 10% | Fall, 10% chance earlier | Fall, 50% | Fall, 90% |
|---|---|---|---|---|---|---|
| Light frost, 32°F | May 8 | May 21 | Jun 3 | Sep 9 | Sep 21 | Oct 2 |
| Hard freeze, 28°F | Apr 29 | May 11 | May 25 | Sep 16 | Sep 28 | Oct 11 |
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 Williston Sloulin International Airport (USW00094014) sits 1.2 miles from the center of Williston at 1,902 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 Williston, ND?
The average last frost date in Williston is May 21, based on NOAA 1991–2020 climate normals. There is a 10% chance of frost after June 3.
When is the first frost in Williston?
The first frost in fall usually comes around September 21. One year in ten it arrives before September 9.
How long is the growing season in Williston?
About 123 days between the average last and first frost.
When should I plant tomatoes in Williston?
Plant tomato seedlings outside from May 28 to June 11. Start seeds indoors six to eight weeks earlier.
Nearby in North Dakota
- DickinsonMay 20
- MinotMay 10
- MandanMay 13
- BismarckMay 10
- Grand ForksMay 10
- West FargoMay 4
- FargoMay 4