How Much Snow Missoula and the Bitterroot Valley Actually Get

How much snow does Missoula get in an average year?

The station at Missoula International Airport has a 1991-2020 normal annual snowfall of 43.0 inches. The National Weather Service office northwest of town keeps its own cooperative station (listed as Missoula 6 NW WFO), and its normal is 42.9 inches, so the two agree closely. Those are averages across 30 winters, which means any single winter can land well above or below them.

NOAA describes a normal as the 30-year average of a station's measurements for a uniform period, and the current set covers 1991 through 2020. The normals were first released in 2021, so they describe the climate of the last three decades, not a forecast for this winter.

Which months bring the most snow?

December is the snowiest month at the Missoula airport, with a normal of 11.6 inches, followed by January at 9.9 and February at 8.5. November averages 5.4 inches and March 5.0. April still averages 1.3 inches, October 0.9 and May 0.3, which is why a mid-spring storm in Missoula is unusual but never surprising.

Put another way, NOAA's seasonal normals put 30.0 inches in December through February, 6.4 inches in September through November and 6.6 inches in March through May. Roughly seven of every ten inches fall in the three core winter months. That is the window when a snow route is busiest and when storage space for plowed snow starts to run short on tight lots.

How many storms are big enough to plow?

Fewer than most people think. NOAA counts the average number of days per year with snowfall at or above set thresholds. At the Missoula airport, measurable snow (0.1 inch or more) falls on about 40 days a year. Snowfall of 1 inch or more happens on about 13.8 days, 2 inches or more on 6.4 days, 3 inches or more on 3.8 days, and 5 inches or more on only 1.3 days. Days with 10 inches or more round to zero in the 30-year average.

This is the practical number for a property owner. Missoula's snow mostly arrives as frequent small events, not a few huge ones. A driveway or lot sees many light snowfalls that a snow service trigger depth may or may not cover, a handful of plowable storms each winter, and only occasionally a big one. It is also why ice management matters as much as plowing here: small snowfalls that melt and refreeze do most of the damage to footing.

How long does snow stay on the ground?

At the Missoula airport, snow depth of 1 inch or more is on the ground for an average of about 60.6 days a year, and 5 inches or more for about 22.1 days. Depth of 10 inches or more averages only 3.9 days. By month, January averages 19.9 days with at least an inch on the ground, December 16.2, February 14.1, and March 4.8.

The National Weather Service Missoula office publishes its own white Christmas statistics for Missoula going back to 1948. It reports at least 1 inch of snow on the ground on 67 percent of Christmas Days, 3 inches or more on 38 percent and 6 inches or more on 16 percent. Snow actually fell on 30 percent of Christmas Days. The snowiest was 7.6 inches in 1996, the same year Christmas had the deepest snow on record, 21 inches.

Does the Bitterroot Valley get more or less snow than Missoula?

The station records suggest less on the valley floor, but the Bitterroot data comes with a caution. The Stevensville cooperative station has a published normal annual snowfall of 17.1 inches, with 6.8 inches in December, 4.0 in January and 3.0 in February. NOAA flags that snowfall normal as Provisional and lists only 12 years of data behind the annual figure. NOAA's readme defines Provisional as meeting World Meteorological Organization availability standards for 10 or more years, with missing months that could not be filled from surrounding stations. Missoula's airport figures, by contrast, carry the Standard flag, which requires 24 or more years.

Hamilton and Darby have full temperature and precipitation normals in the 1991-2020 set, but no published snowfall normal at all, so there is no official 30-year snowfall figure to quote for the south end of the valley. We would rather say that plainly than borrow a number from somewhere else. What the precipitation normals do show is that Darby, near the mountains at the south end, has the highest normal annual precipitation of the stations we checked at 15.11 inches, against 13.60 at Hamilton, 12.45 at Stevensville and 14.11 at the Missoula airport.

Anyone who lives on the benches or up a side drainage knows that elevation and position change the picture. The stations sit on or near the valley floor. These numbers do not describe properties higher on the Sapphire or Bitterroot foothills or up toward Lolo Pass, so do not assume they apply there.

How cold is a normal winter in the valleys?

January's normal high at the Missoula airport is 31.6 degrees Fahrenheit and its normal low is 18.0. December is slightly colder by day at 30.9 and 17.8. The Bitterroot stations run a few degrees warmer by day: Hamilton's normal January high is 35.1 with a low of 18.9, Stevensville's 34.6 and 18.9, and Darby's 33.9 and 19.2.

Nights at or below 0 degrees average 6.7 a year at the Missoula airport, 7.0 at Hamilton and 6.7 at both Stevensville and Darby. Those are the nights that test pipes, outdoor faucets and backflow assemblies. If yours were not drained in the fall, see our guide to winterizing an irrigation system.

Why do so many days freeze at night and thaw by afternoon?

Because valley winter days hover around the freezing mark. The Missoula airport averages 172.5 days a year with a low at or below 32 degrees, but only 42.8 days when the high stays at or below 32. The difference, roughly 130 days, are days that freeze overnight and climb above freezing at some point. At Hamilton the counts are 172.6 and 29.1, so the gap is even wider. In December through February alone, Missoula averages 85.6 freezing nights and 35.5 days that stay below freezing all day, leaving about 50 winter days that cross the line both ways.

That pattern drives a lot of winter property damage and most slip hazards. We cover the mechanics in freeze-thaw cycles and what they do to a property and the footing side in our guide to black ice on driveways and walks.

When is the first and last freeze?

NOAA's freeze probability normals put the median date of the first 32 degree fall freeze at the Missoula airport on September 26, and the median last spring freeze on May 16. In the Bitterroot the season is shorter: Hamilton's medians are September 22 and May 21, Stevensville's September 19 and May 22, and Darby's September 23 and May 24. Median means half of years are earlier and half later.

For outdoor water, these dates matter more than the snow numbers. Sprinkler blowouts and hose bib shutoffs need to be done before the first hard freeze, and in many Bitterroot years that comes in September. Our sprinkler blowout and winterization service is booked around those dates.

Will this winter be close to normal?

Normals describe the last 30 years, not the coming season. For 2026-27 specifically, the Climate Prediction Center's ENSO discussion issued 8 October 2026 had an El Nino Advisory in effect, and its seasonal discussion issued 15 October 2026 favored above-normal temperatures across the northern tier and below-normal precipitation for the northern Rockies. Those are odds, not a snowfall forecast, and a single storm can still deliver a large share of a season's total.

We cover what that means for roots, lawns and pipes in a low-snow winter. Plan for the normal season anyway: it costs little to have the snow service and the stakes in place, and a lot to arrange them during the first big storm.

How should I use these numbers to plan for winter?

Use them for scale, not as a promise. A 43 inch season delivered as many small snowfalls means you need reliable light-snow and ice handling more than you need a giant plow. A drive that faces north or sits in a cold pocket will keep snow and ice well past the airport's 60 days of cover. And a Bitterroot property should not assume the Stevensville figure applies to it, especially off the valley floor.

This page is part of our Montana Winter Property Guide. For how the storms themselves behave, read winter storm types in western Montana. For year-round clearing, our snow and 24-hour storm services cover driveways, private roads, lots and walks, and residential snow removal is set up on routes before the season starts. Call HJ Property Care & Tree Service at (406) 215-7319 or request a free estimate for winter service in Missoula and the Bitterroot Valley.

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