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.
Frost dates matter for concrete, which must not freeze in its first 48 hours, for paint and caulk that need nights above their minimum, and for lawn care, since crabgrass preventer goes down as the soil warms in spring. See how late in fall you can stain, paint or seal.
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. 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. 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.
Check this week’s hour-by-hour verdict with the deck staining forecast.
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. 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. 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.
Check this week’s hour-by-hour verdict with the exterior painting forecast.
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. 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. 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.
Check this week’s hour-by-hour verdict with the concrete pouring forecast.
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. 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. 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.
Check this week’s hour-by-hour verdict with the driveway sealing forecast.
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. 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. 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.
Check this week’s hour-by-hour verdict with the lawn fertilizer forecast.
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). If you live between them, expect something in between, and higher ground to be cooler with a shorter season.
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 at least 0.1 inch of rain or melted snow. Freezing nights: average nights a month at or below 32°F. Humidity is calculated from NOAA hourly normal temperature and dew point at 3 PM.
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 |
Use the averages, then check the forecast
These ratings describe a typical month, not a particular week. A warm spell in a “poor” month can give you a good day, and a wet week can spoil a “good” one. Use this page to plan the season, then check the 7-day forecast for your ZIP code before you buy materials or book help. Each project forecast checks the hours after you finish too: overnight lows, dew and rain that would ruin fresh stain, paint, sealer or concrete.
About this data
Monthly temperatures, rain days, snowfall and freeze dates are NOAA National Centers for Environmental Information (NCEI) U.S. Climate Normals for 1991–2020 at BISMARCK, FARGO HECTOR INTL AP. Ratings apply the same temperature limits as our forecasts (for example, 50°F or warmer for deck stain and driveway sealer, and no freezing nights for new concrete) to the average month. Your product label always takes priority.
Frequently asked questions
When is the best time to stain a deck in North Dakota?
In Bismarck, June–August. In Fargo, June–September. Look for at least 24 dry hours before and after, and nights above about 40°F. The deck staining forecast checks your exact week.
When is the last frost in North Dakota?
Bismarck: around May 14; Fargo: around May 10. These are median dates from NOAA 1991–2020 normals, so a freeze after them happens in about half of years. Low spots and valleys freeze later in spring.
Can you pour concrete in winter in North Dakota?
Yes, but it needs 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. Most sealers need 50°F or warmer for 24 hours and a dry day after. See the driveway sealing forecast.