Scenic Bridge · Photo: Kristi Hager, Photographer · Public domainPrecipitation in Potomac trails that of 94% of U.S. towns: 14 inches a year
Deep winter brings January lows near 13°. June is the wettest month, March the driest. In January, nights here are colder than in 89% of U.S. towns. The outdoor season runs from June to August, with highs of 73–83°.
A year in Potomac at a glance
Each month’s typical high and low, and what it brings.
What stands out about Potomac’s climate
Compared with towns across the U.S., with Potomac’s place in Montana beside it.
What a year in Potomac feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
A freeze is possible in every month
About 247 nights a year fall to 32° or below, and 24 to 0° or below. Frost and day counts come from NOAA’s station at Potomac, MT, 0.7 miles from the town’s center, at about the same height.
The 2023 USDA map puts Potomac’s center in zone 4b: the coldest night of a typical winter, averaged over 1991–2020, reaches about −22°. Plant labels use the zone; frost dates tell you when to plant.
Freezing nights by month
Average nights at or below 32°
90° days by month
Average days at 90° or more
About 52 inches of snow a winter
Snow, measured at Potomac, MT, falls mostly in January. Precipitation (rain plus melted snow) adds up to 14 inches a year; June is the wettest month and March the driest. Rain or snow falls on about 81 days a year.
Rain + melted snow by month
Inches of water
Snowfall by month
Inches of snow
Heating and cooling a home in Potomac
99% of the work is heating, so the furnace matters far more than the air conditioner. Months averaging under 55° run from September through May.
Degree days add up how far each day’s average falls below (heating) or rises above (cooling) 65° over a year. NOAA normals at Potomac, MT.
Living with Potomac’s climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
Zone 4b, and frost can come in any month. The longest frost-free stretch in half of years is about 45 days.
Months with highs of 62–84° and lows of 40° or more: June, July and August.
Parks & trails →Of the yearly building losses FEMA expects in Potomac from natural hazards, avalanches are the largest share (54%); heat waves, cold waves, winter storms and ice storms together are 9%. Normals are averages; the hazards page covers the extremes.
Natural hazards →Potomac and similar climates
TownRatings has no climate map of the towns around Potomac yet.
Climates most like Potomac’s, farther away
TownRatings’ own comparison of NOAA 1991–2020 normals, not a NOAA product: places of 5,000+ at least 150 miles away, one per state, closest on January low, July high, precipitation and snow.
| Town | Jan. low | July high | Precip. | Snow |
|---|---|---|---|---|
| Potomac, MT | 13° | 83° | 14" | 52" |
| Cody, WY | 14° | 85° | 11" | 45" |
| Rexburg, ID | 12° | 84° | 13" | 70" |
| Gleneagle, CO | 14° | 84° | 21" | 55" |
| Doney Park, AZ | 17° | 86° | 16" | 52" |
Temperatures and precipitation come from NOAA’s 5 km grid; snow and day counts from the stations named on this page.
Warmer than it used to be
The last 30 years in Potomac averaged 1.4° warmer than the 1900s. The biggest change is in January (+4.1°).
A bigger shift than in 52% of U.S. towns.
Change by month
The two periods overlap (1991–2000 is in both), which makes the gap a little smaller than it would be between separate periods.
How Potomac compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Potomac’s place among Montana’s.
Potomac weather by month
Highs, lows and precipitation from NOAA’s grid at Potomac’s center; snow, wet days and snow on the ground from Potomac, MT. 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | Snow on ground | 30-yr range |
|---|---|---|---|---|---|---|---|
| January | 32° | 13° | 1.1" | 15.5" | 8 | 30 | 13° – 30° |
| February | 37° | 14° | 1.0" | 7.2" | 6 | 25 | 12° – 33° |
| March | 47° | 22° | 0.8" | 4.6" | 6 | 14 | 26° – 41° |
| April | 55° | 28° | 1.1" | 1.3" | 6 | 1 | 37° – 49° |
| May | 65° | 35° | 1.7" | 0.4" | 8 | 0 | 45° – 55° |
| June | 73° | 41° | 2.1" | 0.0" | 10 | 0 | 53° – 66° |
| July | 83° | 45° | 0.8" | 0.0" | 5 | 0 | 55° – 72° |
| August | 83° | 44° | 0.9" | 0.0" | 4 | 0 | 58° – 67° |
| September | 72° | 37° | 1.0" | 0.2" | 5 | 0 | 51° – 60° |
| October | 56° | 28° | 1.3" | 1.9" | 7 | 1 | 35° – 49° |
| November | 40° | 21° | 1.3" | 7.4" | 8 | 7 | 24° – 38° |
| December | 31° | 13° | 1.3" | 13.3" | 8 | 24 | 15° – 28° |
| Year | 56° | 28° | 14.3" | 51.8" | 81 | 102 |
How much a month can swing
A normal is an average. February swings the most: from 1991 to 2020 its average ranged from 12° to 33°. September is the most reliable, staying within 9°.
Where Potomac’s numbers come from
Normals are 30-year averages, not a forecast. How TownRatings reads climate data →
- Temperatures and precipitation: NOAA’s gridded 1991–2020 normals for the 5 km cell at Potomac’s center.
- Snow: Potomac, MT (NOAA station in town).
- Frost, freezing nights, 90° and 100° days, heating and cooling: Potomac, MT, 0.7 miles from the town’s center, at about the same height; the nearest station that passes our checks for distance, height and agreement with the grid.
- Growing zone: USDA Plant Hardiness Zone Map, 2023. USDA Agricultural Research Service and PRISM Group, Oregon State University, prism.oregonstate.edu/phzm, accessed 8 Oct 2026.
- Then and now: NOAA’s gridded normals for 1901–2000 at the same cell.
- Storms and extremes: FEMA National Risk Index (expected annual losses to buildings).
Common questions about Potomac’s climate
What is the weather like in Potomac?
A typical July afternoon reaches 83°, a January night drops to 13°, and about 52 inches of snow falls in a normal winter. Colder January nights than 89% of U.S. towns; cooler July afternoons than 68% of U.S. towns.
How cold does it get in Potomac in winter?
December nights average 13°. About 247 nights a year reach 32° or below and 24 reach 0° or below. In the coldest December of the last 30 years the month averaged 15°.
How much snow does Potomac get?
About 52 inches in a normal winter at Potomac, MT, most of it in January, with snow on the ground about 102 days a year.
How hot does it get in Potomac?
July, with a typical high of 83° and a low of 45°. About 16 days a year reach 90° (Potomac, MT).
When is the first and last frost in Potomac?
There is no reliable frost-free season: at Potomac, MT, every month has nights at 32° or below, about 247 a year. In half of years the longest stretch without a freeze is about 45 days.
What growing zone is Potomac in?
Zone 4b on the 2023 USDA Plant Hardiness Zone Map: the coldest night of a typical winter reaches about −22°.
What is the best time of year to visit Potomac?
By one simple rule (highs of 62–84° and lows of 40° or more), June, July and August. The rule is ours, not NOAA’s; the month table has the numbers to judge by.
Is Potomac getting warmer?
Yes: 1991–2020 averaged 1.4° warmer than 1901–2000 on NOAA’s grid. A bigger shift than 52% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in Potomac.
Source: NOAA NCEI U.S. Climate Normals, 1991–2020 and 1901–2000; USDA/PRISM 2023 hardiness zones; FEMA National Risk Index. Today’s forecast: National Weather Service.