North Dakota weather and outdoor projects
North Dakota has some of the coldest winters in the lower 48 and a short, warm summer. Fargo in the Red River Valley is a bit more humid, while Bismarck and the west are drier and windier. The last spring freeze often comes in mid-May, and the first fall freeze in mid- to late September.
That leaves a short window, roughly June through August, for staining, painting and concrete. Wind is often strong, so spraying needs calm mornings. Concrete poured near either end of the season needs protection against cold nights.
Frost dates in North Dakota
In Bismarck, the median last spring freeze (32°F) is around May 14 and the median first fall freeze is around September 27, a frost-free season of about 136 days.
In Fargo, the median last spring freeze (32°F) is around May 10 and the median first fall freeze is around September 30, a frost-free season of about 143 days.
How North Dakota compares with other states
Bismarck has the shortest frost-free season of the 50 state main stations (136 days). Bismarck has the 2nd-most freezing nights of the 50 state main stations (184 a year). Bismarck is tied for the 6th-shortest deck staining season of the 50 state main stations (3 good months).
| Measure (Bismarck) | Value | Rank, highest first |
|---|---|---|
| Deck staining season | 3 good months | 38th of 50 |
| Frost-free season | 136 days | 50th of 50 |
| Freezing nights | 184 a year | 2nd of 50 |
| Rainy days | 42 a year with 0.1 in or more | 41st of 50 |
| Days at 90°F or hotter | 21 a year | 31st of 50 |
| Summer afternoons | 42% humidity at 3 PM, June–August | 38th of 47 |
Best time to stain a deck in North Dakota
In Bismarck, the most reliable months are June–August. May and September can also work on the right days (average highs May 68°F, Sep 73°F). November–March is too cold, with average highs around 32°F. In April and October, nights average about 32°F, too cold for the coating to dry and cure overnight. In May and September, nights average about 44°F, so finish early on mild days and check the overnight low.
In Fargo, the most reliable months are June–September. May can also work on the right days (average highs May 69°F). November–April is too cold, with average highs around 32°F. In October, nights average about 35°F, too cold for the coating to dry and cure overnight. In May, nights average about 44°F, so finish early on mild days and check the overnight low.
Best time to paint outside in North Dakota
In Bismarck, the most reliable months are June–September. May can also work on the right days (average highs May 68°F). November–March is too cold, with average highs around 32°F. In April and October, nights average about 32°F, too cold for the coating to dry and cure overnight. In May, nights average about 42°F, so finish early on mild days and check the overnight low.
In Fargo, the most reliable months are June–September. May and October can also work on the right days (average highs May 69°F, Oct 56°F). November–March is too cold, with average highs around 28°F. In April, nights average about 32°F, too cold for the coating to dry and cure overnight. In May, nights average about 44°F, so finish early on mild days and check the overnight low. October is cool, with highs around 56°F, so choose the warmest afternoons.
Best time to pour concrete in North Dakota
In Bismarck, the most reliable months are June–August. May and September can also work on the right days (average highs May 68°F, Sep 73°F). October–April averages about 25 nights a month at or below 32°F, so fresh concrete needs blankets or heated enclosures. May and September bring about 3 freezing nights a month, so pick a mild spell and keep curing blankets on hand.
In Fargo, the most reliable months are June–September. May can also work on the right days (average highs May 69°F). October–April averages about 24 nights a month at or below 32°F, so fresh concrete needs blankets or heated enclosures. May brings about 3 freezing nights a month, so pick a mild spell and keep curing blankets on hand.
Best time to seal a driveway in North Dakota
In Bismarck, the most reliable months are June–August. May and September can also work on the right days (average highs May 68°F, Sep 73°F). October–April is too cold, with average highs around 39°F. In May and September, nights average about 44°F, so finish early on mild days and check the overnight low.
In Fargo, the most reliable months are June–August. May and September can also work on the right days (average highs May 69°F, Sep 72°F). October–April is too cold, with average highs around 36°F. In May and September, nights average about 46°F, so finish early on mild days and check the overnight low.
Best time to fertilize or treat a lawn in North Dakota
In Bismarck, the most reliable months are May–September. April and October can also work on the right days (average highs Apr 56°F, Oct 57°F). November–March is too cold, with average highs around 32°F. April and October are cool, with highs around 57°F, so choose the warmest afternoons.
In Fargo, the most reliable months are May–September. April and October can also work on the right days (average highs Apr 54°F, Oct 56°F). November–March is too cold, with average highs around 28°F. April and October are cool, with highs around 55°F, so choose the warmest afternoons.
How the weather differs across North Dakota
| Place | Hottest month avg high | Coldest month avg low | Rain per year | Last spring freeze | First fall freeze |
|---|---|---|---|---|---|
| Bismarck | 85°F | 2°F | 19 in | May 14 | September 27 |
| Fargo | 82°F | 0°F | 24 in | May 10 | September 30 |
Of the places above, Fargo has the most good months for staining, painting and concrete combined (12 job-months), and Bismarck has the fewest (10).
Monthly weather in Bismarck
| Month | Avg high | Avg low | Wet days* | Rain | 3 PM humidity | Freezing nights |
|---|---|---|---|---|---|---|
| January | 23°F | 2°F | 2 | 0.5 in | 68% | 31 |
| February | 28°F | 7°F | 2 | 0.5 in | 63% | 28 |
| March | 41°F | 19°F | 2 | 0.8 in | 52% | 28 |
| April | 56°F | 30°F | 4 | 1.3 in | 39% | 18 |
| May | 68°F | 42°F | 6 | 2.5 in | 41% | 4 |
| June | 78°F | 53°F | 6 | 3.4 in | 45% | 0 |
| July | 85°F | 58°F | 6 | 3.1 in | 42% | 0 |
| August | 84°F | 56°F | 4 | 2.5 in | 40% | 0 |
| September | 73°F | 46°F | 3 | 1.7 in | 40% | 2 |
| October | 57°F | 33°F | 3 | 1.4 in | 43% | 15 |
| November | 41°F | 19°F | 2 | 0.7 in | 54% | 28 |
| December | 28°F | 8°F | 2 | 0.6 in | 65% | 31 |
*Days with 0.1 inch of rain or more; column notes.
Monthly weather in Fargo
| Month | Avg high | Avg low | Wet days* | Rain | 3 PM humidity | Freezing nights |
|---|---|---|---|---|---|---|
| January | 18°F | 0°F | 2 | 0.7 in | 73% | 31 |
| February | 23°F | 4°F | 2 | 0.7 in | 70% | 27 |
| March | 36°F | 18°F | 3 | 1.3 in | 63% | 27 |
| April | 54°F | 32°F | 4 | 1.5 in | 44% | 16 |
| May | 69°F | 44°F | 6 | 3.1 in | 41% | 3 |
| June | 78°F | 56°F | 7 | 4.3 in | 47% | 0 |
| July | 82°F | 59°F | 6 | 3.1 in | 50% | 0 |
| August | 81°F | 57°F | 4 | 2.6 in | 48% | 0 |
| September | 72°F | 48°F | 5 | 2.7 in | 46% | 1 |
| October | 56°F | 35°F | 5 | 2.2 in | 50% | 12 |
| November | 38°F | 21°F | 3 | 1.0 in | 62% | 26 |
| December | 24°F | 8°F | 3 | 0.9 in | 72% | 31 |
Source: NOAA NCEI U.S. Climate Normals 1991–2020 for BISMARCK, FARGO HECTOR INTL AP. See how the ratings work and how late in fall you can stain, paint or seal.
Frequently asked questions
When is the best time to stain a deck in North Dakota?
In Bismarck, June–August. In Fargo, June–September.
When is the last frost in North Dakota?
Bismarck: around May 14; Fargo: around May 10.
Can you pour concrete in winter in North Dakota?
Yes, with cold-weather practices: Bismarck averages about 89 freezing nights from December to February, so fresh concrete needs insulated blankets, a heated enclosure or an accelerated mix, and must not freeze in the first 48 hours. Many homeowners wait for spring.
What months are best for sealing a driveway in North Dakota?
In Bismarck, June–August. In Fargo, June–August.