Frost dates in North Dakota

NOAA 1991–2020 normals for a 32 °F freeze. Your own yard can run a little either side.

Short answer

Across 14 NOAA weather stations in North Dakota, the average last spring frost runs from May 6 at Devils Lake Kdlr to May 24 at Hettinger Muni Airport. The first fall frost comes as early as September 18 at Hettinger Muni Airport and as late as October 5 at Devils Lake Kdlr. Planting zones near these stations run from 3b to 4b.

Find yours by ZIP code

The table below is by weather station. For the station nearest you, and your planting zone, type your ZIP code.

North Dakota frost dates by weather station

Station	Last spring frost	First fall frost	Frost-free	Zone nearby
Bismarck 1,658 ft	May 14 1 in 10 after May 27	September 27 1 in 10 by September 15	136 days	4a
Devils Lake Kdlr 1,464 ft	May 6 1 in 10 after May 19	October 5 1 in 10 by September 26	152 days	4a
Fargo Hector Intl Airport 900 ft	May 10 1 in 10 after May 23	September 30 1 in 10 by September 18	143 days	4a
Garrison 1,910 ft	May 14 1 in 10 after May 28	September 26 1 in 10 by September 13	135 days	–
Grand Forks Intl Airport 842 ft	May 16 1 in 10 after May 31	September 27 1 in 10 by September 15	134 days	4a
Hettinger Muni Airport 2,705 ft	May 24 1 in 10 after June 10	September 18 1 in 10 by September 1	117 days	4b
Jamestown 38 WSW 1,920 ft	May 14 1 in 10 after May 26	September 27 1 in 10 by September 15	136 days	4a
Jamestown Muni Airport 1,494 ft	May 11 1 in 10 after May 24	September 28 1 in 10 by September 15	140 days	4b
Medora 7 E 2,771 ft	May 9 1 in 10 after May 21	September 30 1 in 10 by September 15	144 days	4b
Minot Intl Airport 1,665 ft	May 10 1 in 10 after May 22	October 1 1 in 10 by September 19	144 days	4a
Northgate 5 ESE 1,842 ft	May 20 1 in 10 after June 2	September 19 1 in 10 by September 7	122 days	–
Pembina 790 ft	May 16 1 in 10 after May 31	September 29 1 in 10 by September 17	136 days	3b
Theodore Roosevelt Airport 2,580 ft	May 18 1 in 10 after May 31	September 25 1 in 10 by September 12	130 days	4b
Williston Sloulin Intl Airport 1,902 ft	May 21 1 in 10 after June 3	September 21 1 in 10 by September 9	123 days	4a

The average date is NOAA's 50% date: half of years have a later last frost, or an earlier first one. Plan by the 1-in-10 date if a freeze would cost you plants. Stations are NOAA's main weather stations, mostly airports. “Zone nearby” is the USDA 2023 zone of the nearest ZIP code within 10 miles. NOAA counts the frost season from August to July, so in the warmest places the “first fall” freeze lands after New Year.

How these dates work

Frost dates come from NOAA's 1991 to 2020 Climate Normals, which work out from each weather station's daily lows how likely the last spring freeze and the first fall freeze (32 °F) are by each date. We use the station nearest the middle of your ZIP code and show its height and distance, since a station on a hill or by a lake can differ from your yard.

The average date is the 50% date: half of years have a freeze after the spring date or before the fall one. The 1-in-10 dates are NOAA's 10% dates, the ones to plan by if a late freeze would cost you plants. Within one yard, cold air pools in low spots while walls and paving hold heat, so some corners freeze before others.

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