Best Time for Outdoor Projects in Montana

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.

How Montana compares with other states

Billings is tied for the 5th-shortest frost-free season of the 50 state main stations (156 days). Billings is tied for the 6th-shortest deck staining season of the 50 state main stations (3 good months). Billings has the 7th-least humid summer afternoons of the 47 state main stations (28% humidity at 3 PM, June–August).

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 (average highs May 67°F, Jul 87°F). 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 (average highs May 66°F, Jun 73°F, Sep 73°F). 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.

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 (average highs May 66°F, Sep 73°F). 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.

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 (average highs May 67°F, Oct 59°F). 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 (average highs May 66°F, Sep 73°F). 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.

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 (average highs May 67°F, Sep 74°F). 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.

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 (average highs Apr 57°F, Jul 87°F, Oct 59°F). 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 (average highs Apr 56°F, Oct 56°F). 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.

Lawn fertilizer forecast →

How the weather differs across Montana

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).

Monthly weather in Billings

*Days with 0.1 inch of rain or more; column notes.

Monthly weather in Missoula