Montana weather and outdoor projects
Montana has a dry continental climate with cold winters and warm, dry summers. Billings in the east sees hot summer days and frequent wind, while Missoula in the western valleys is cooler with more winter cloud. Summer nights cool off quickly, often into the 50s or lower, even after warm days.
July and August are the most reliable months for staining and painting. Spring snow is possible into May, and the first fall frost often comes in September. Wildfire smoke in late summer can settle on fresh finishes. Strong chinook winds in winter cause big temperature swings east of the mountains.
Frost dates in Montana
In Billings, the median last spring freeze (32°F) is around May 4 and the median first fall freeze is around October 7, a frost-free season of about 156 days.
In Missoula, the median last spring freeze (32°F) is around May 16 and the median first fall freeze is around September 26, a frost-free season of about 130 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 Montana
In Billings, the most reliable months are June and August–September. May and July can also work on the right days. November–March is too cold, with average highs around 41°F. In April and October, nights average about 36°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. July is hot, with highs near 87°F, so start early and keep out of full afternoon sun.
In Missoula, the most reliable months are July–August. May–June and September can also work on the right days. November–March is too cold, with average highs around 37°F. In April and October, nights average about 32°F, too cold for the coating to dry and cure overnight. In May–June and September, nights average about 43°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 Montana
In Billings, the most reliable months are June and August–September. April–May, July and October can also work on the right days. November–March is too cold, with average highs around 41°F. April is cool, with highs around 57°F, so choose the warmest afternoons. In May and October, nights average about 40°F, so finish early on mild days and check the overnight low. July is hot, with highs near 87°F, so start early and keep out of full afternoon sun.
In Missoula, 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 37°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 41°F, so finish early on mild days and check the overnight low.
Check this week’s hour-by-hour verdict with the exterior painting forecast.
Best time to pour concrete in Montana
In Billings, the most reliable months are June–September. May and October can also work on the right days. November–April averages about 22 nights a month at or below 32°F, so fresh concrete needs blankets or heated enclosures. May and October bring about 5 freezing nights a month, so pick a mild spell and keep curing blankets on hand.
In Missoula, the most reliable months are June–August. May and September 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 and September bring 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 Montana
In Billings, 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 46°F. May is cool, with highs around 67°F, so choose the warmest afternoons. In September, nights average about 49°F, so finish early on mild days and check the overnight low.
Missoula has no month that is easy for this job on average; the best chances come in June–September. October–April is too cold, with average highs around 43°F. In May, nights average about 40°F, too cold for the coating to dry and cure overnight. In June–September, nights average about 48°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 Montana
In Billings, the most reliable months are May–June and August–September. April, July and October can also work on the right days. November–March is too cold, with average highs around 41°F. April and October are cool, with highs around 58°F, so choose the warmest afternoons. July is hot, with highs near 87°F, so start early and keep out of full afternoon sun.
In Missoula, 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 37°F. April and October are cool, with highs around 56°F, so choose the warmest afternoons.
Check this week’s hour-by-hour verdict with the lawn fertilizer forecast.
How the weather differs across Montana
| Place | Hottest month avg high | Coldest month avg low | Rain per year | Last spring freeze | First fall freeze |
|---|---|---|---|---|---|
| Billings | 87°F | 18°F | 14 in | May 4 | October 7 |
| Missoula | 85°F | 18°F | 14 in | May 16 | September 26 |
Of the places above, Billings has the most good months for staining, painting and concrete combined (10 job-months), and Missoula has the fewest (8). If you live between them, expect something in between, and higher ground to be cooler with a shorter season.
Monthly weather in Billings
| Month | Avg high | Avg low | Wet days* | Rain | 3 PM humidity | Freezing nights |
|---|---|---|---|---|---|---|
| January | 36°F | 18°F | 2 | 0.6 in | 50% | 27 |
| February | 39°F | 20°F | 2 | 0.6 in | 43% | 24 |
| March | 49°F | 27°F | 3 | 0.9 in | 37% | 21 |
| April | 57°F | 35°F | 5 | 1.7 in | 36% | 11 |
| May | 67°F | 44°F | 6 | 2.4 in | 36% | 2 |
| June | 77°F | 52°F | 5 | 2.2 in | 34% | 0 |
| July | 87°F | 59°F | 3 | 1.2 in | 26% | 0 |
| August | 86°F | 58°F | 2 | 0.9 in | 24% | 0 |
| September | 74°F | 49°F | 3 | 1.4 in | 29% | 0 |
| October | 59°F | 37°F | 4 | 1.4 in | 37% | 8 |
| November | 46°F | 27°F | 2 | 0.6 in | 43% | 21 |
| December | 36°F | 19°F | 2 | 0.6 in | 49% | 28 |
*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 Missoula
| Month | Avg high | Avg low | Wet days* | Rain | 3 PM humidity | Freezing nights |
|---|---|---|---|---|---|---|
| January | 32°F | 18°F | 3 | 1.0 in | 71% | 30 |
| February | 37°F | 21°F | 3 | 0.9 in | 60% | 26 |
| March | 48°F | 27°F | 3 | 0.9 in | 45% | 25 |
| April | 56°F | 32°F | 4 | 1.4 in | 38% | 15 |
| May | 66°F | 40°F | 5 | 1.8 in | 36% | 4 |
| June | 73°F | 46°F | 6 | 2.1 in | 35% | 0 |
| July | 85°F | 52°F | 3 | 0.8 in | 24% | 0 |
| August | 84°F | 50°F | 3 | 0.8 in | 23% | 0 |
| September | 73°F | 42°F | 3 | 1.0 in | 31% | 2 |
| October | 56°F | 32°F | 4 | 1.2 in | 44% | 15 |
| November | 40°F | 25°F | 4 | 1.2 in | 61% | 26 |
| December | 31°F | 18°F | 4 | 1.1 in | 71% | 30 |
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 BILLINGS LOGAN INTL AP, MISSOULA 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 Montana?
In Billings, June and August–September. In Missoula, July–August. 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 Montana?
Billings: around May 4; Missoula: around May 16. 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 Montana?
Yes, but it needs cold-weather practices. Billings averages about 79 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 Montana?
In Billings, June–August. In Missoula, conditions are marginal in most months, so choose warm, dry spells. Most sealers need 50°F or warmer for 24 hours and a dry day after. See the driveway sealing forecast.