Potomac, Montana climate: Normal weather by month, frost dates and records
Potomac's normal year runs from 9°F December nights to 82°F July afternoons, with 15.1 inches of precipitation and 52 inches of snow a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 4.1°C, December lows of −13°C, July highs of 28°C, 384 mm of precipitation a year.
- NOAA stationPotomac
- Station IDUSC00246685
- Location46.88°N 113.56°W
- Elevation3,690 ft (1,125 m)
- Population (census place)7
On October 22, the normal high in Potomac is 52°F and the normal low 22°F, and the chance of measurable rain or snow is 23%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Potomac.
- Jan 30° 8°
- Feb 35° 9°
- Mar 46° 18°
- Apr 54° 24°
- May 64° 30°
- Jun 71° 38°
- Jul 82° 41°
- Aug 82° 39°
- Sep 71° 32°
- Oct 55° 23°
- Nov 39° 16°
- Dec 29° 9°
Each month: normal high (large) and low, °F. Fill: the month's normal mean, colder blue to hotter red.
What is the weather like in Potomac each month?
July is the warmest month, with normal highs of 82°F; December the coldest, with normal lows of 9°F. The most precipitation falls in June (2.16 in), the least in August (0.62 in).
| Month | High | Low | Mean | Precip. | Snow | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|---|
| January | 30°F | 8°F | 19.1°F | 1.38 | 15.5 | 8 | <1 | 31 | 8 h 50 min |
| February | 35°F | 9°F | 21.7°F | 1.03 | 7.2 | 6 | <1 | 28 | 10 h 20 min |
| March | 46°F | 18°F | 31.5°F | 0.76 | 4.6 | 6 | <1 | 31 | 11 h 50 min |
| April | 54°F | 24°F | 38.8°F | 1.13 | 1.3 | 6 | <1 | 27 | 13 h 30 min |
| May | 64°F | 30°F | 46.9°F | 1.86 | 0.4 | 8 | <1 | 17 | 15 h |
| June | 71°F | 38°F | 54.8°F | 2.16 | 0.0 | 10 | 1 | 5 | 15 h 50 min |
| July | 82°F | 41°F | 61.3°F | 0.83 | 0.0 | 5 | 7 | 2 | 15 h 30 min |
| August | 82°F | 39°F | 60.2°F | 0.62 | 0.0 | 4 | 7 | 4 | 14 h 20 min |
| September | 71°F | 32°F | 51.5°F | 0.91 | 0.2 | 5 | 1 | 16 | 12 h 40 min |
| October | 55°F | 23°F | 39.4°F | 1.46 | 1.9 | 7 | <1 | 27 | 11 h |
| November | 39°F | 16°F | 27.7°F | 1.55 | 7.4 | 8 | <1 | 29 | 9 h 30 min |
| December | 29°F | 9°F | 18.9°F | 1.41 | 13.3 | 8 | <1 | 31 | 8 h 30 min |
| Year (annual) | 55°F | 24°F | 39.3°F | 15.10 | 51.8 | 81 | 16 | 247 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. | Snow |
|---|---|---|---|---|---|
| January | −1°C | −13°C | −7.2°C | 35 mm | 39 cm |
| February | 2°C | −13°C | −5.7°C | 26 mm | 18 cm |
| March | 8°C | −8°C | −0.3°C | 19 mm | 12 cm |
| April | 12°C | −5°C | 3.8°C | 29 mm | 3 cm |
| May | 18°C | −1°C | 8.3°C | 47 mm | 1 cm |
| June | 22°C | 3°C | 12.7°C | 55 mm | 0 cm |
| July | 28°C | 5°C | 16.3°C | 21 mm | 0 cm |
| August | 28°C | 4°C | 15.7°C | 16 mm | 0 cm |
| September | 22°C | 0°C | 10.8°C | 23 mm | 1 cm |
| October | 13°C | −5°C | 4.1°C | 37 mm | 5 cm |
| November | 4°C | −9°C | −2.4°C | 39 mm | 19 cm |
| December | −2°C | −13°C | −7.3°C | 36 mm | 34 cm |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00246685; annual normals. Wet days: 0.01 inch or more; 90°F days and freezing nights: NOAA's day counts. Daylight: sunrise to sunset on the 15th, computed from the latitude.
When is the best weather to visit Potomac?
Normal highs sit between 65°F and 85°F in June, July, August and September. Of those, August has the fewest days with rain (4).
That is a measurement, not a recommendation: it counts the months whose normal afternoon high sits between 65°F and 85°F, where a light layer is enough by day.
Source: NOAA NCEI 1991-2020 monthly normals, station USC00246685.
How hot and how cold does it get in Potomac?
In a normal year in Potomac, 16 days a year reach 90°F (1 of them 100°F or more), 247 nights fall to 32°F or colder and 81 days bring measurable precipitation.
- Days at 90°F or more
- 16a normal year
- Days at 100°F or more
- 1a normal year
- Nights at 32°F or colder
- 247a normal year
- Days that stay below freezing
- 44high of 32°F or less
- Days with 0.01 inch of precipitation
- 81a normal year
- Days with 1 inch of snow or more
- 19a normal year
The highest temperature in this station's record (since 1964) is 103°F, on July 14, 2002; the lowest is −50°F, on December 24, 1983.
The wettest calendar year on that record is 1989, with 20.33 in; the snowiest season is 1975–76, with 89.9 inches.
Source: NOAA NCEI 1991-2020 annual normals, station USC00246685; records: ACIS (NOAA Regional Climate Centers), station USC00246685. Records use complete months only; a month missing more than three days is left out.
How sunny is Potomac?
Over a year 74% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around Potomac, 4.0 kWh per square metre a day. July is the sunniest month (86%) and December the cloudiest (61%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 66% | 1.5 |
| February | 70% | 2.5 |
| March | 69% | 3.7 |
| April | 68% | 4.8 |
| May | 69% | 5.7 |
| June | 74% | 6.5 |
| July | 86% | 7.3 |
| August | 84% | 6.0 |
| September | 79% | 4.5 |
| October | 70% | 2.8 |
| November | 64% | 1.6 |
| December | 61% | 1.2 |
Source: NASA POWER solar climatology, 2001-2020 (CERES SYN1deg). Satellite-based, for the 1-degree cell (about 100 km across) around the station, so it describes the area rather than the airport.
How much heating and cooling does Potomac need?
A normal year in Potomac brings 9,385 heating degree days, 75% more than the median U.S. place (5,373), and 53 cooling degree days, 94% fewer than the median (908). Ten months need 300 or more heating degree days, a monthly mean of about 55°F or colder. For gardens and crops, NOAA counts 1,019 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,425 | 0 |
| February | 1,211 | 0 |
| March | 1,039 | 0 |
| April | 786 | 0 |
| May | 560 | 0 |
| June | 310 | 4 |
| July | 145 | 30 |
| August | 165 | 18 |
| September | 406 | 1 |
| October | 794 | 0 |
| November | 1,118 | 0 |
| December | 1,429 | 0 |
| Year (annual) | 9,385 | 53 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00246685. A degree day is one degree of a day's mean temperature below 65°F (heating) or above it (cooling); utilities use them to estimate energy use.
Has Potomac been warmer than normal lately?
2025 averaged 42.7°F, 3.4°F above the 1991-2020 normal of 39.3°F. 3 of the 3 complete years since 2021 ran warmer than the normal.
| Year | Mean | Against normal | Precip. | Snow |
|---|---|---|---|---|
| 2021 | 41.3°F | +2.0°F | 11.90 | 64.3 |
| 2023 | 41.1°F | +1.8°F | 11.58 | – |
| 2025 | 42.7°F | +3.4°F | 13.44 | – |
Source: observed years: ACIS, station USC00246685. A year counts only with all twelve months complete.
How does Potomac's climate compare?
Potomac is warmer than 9 of the other 140 places with their own NOAA record in Montana, and wetter than 74. Across the 7,247 U.S. stations with normals, its annual mean of 39.3°F is warmer than 5%.
In the Köppen classification computed from these normals, Potomac is Dfb: continental, no dry season, warm summer. What the classes mean.
Places with the most similar year elsewhere
Measured month by month on the normal high, low and precipitation, among places of 20,000 or more people in other states:
Source: NOAA NCEI 1991-2020 normals for every station PlainClimate covers. Similarity: the root-mean-square difference of the 36 monthly figures, precipitation weighted so an inch counts like 6°F.
Which places near Potomac share this climate record?
3 places have no NOAA station with 1991-2020 normals of their own, and this station is the nearest full record. A place's own climate can differ from these figures, by several degrees where it sits much higher or lower than the station, nearer the coast, or inside a large city's heat; for the larger places the next nearest records are named with their yearly mean, so the spread around them is visible, and places of 50,000 or more have their own page with NOAA's gridded normals.
- Clinton, MT884 people · 10 mi SW
- Turah, MT507 people · 13 mi W
- Twin Creeks, MT435 people · 8 mi W
Source: Census Bureau 2024 Gazetteer (place centers) and Vintage 2024 population estimates. Distance and direction from the station to each place's center.
Questions about Potomac's climate
What is the coldest month in Potomac?
December, with a normal high of 29°F and a normal low of 9°F. The warmest is July (82°F by day, 41°F at night).
Does it snow in Potomac?
Yes: 52 inches in a normal year, falling on 24 days with 0.1 inch or more, the most in January (15.5 inches).
What is the rainiest month in Potomac?
June, with 2.16 in of precipitation in a normal year; the driest is August with 0.62 in.
What plant hardiness zone is Potomac in?
The USDA's 2023 map puts Potomac in zone 5b in ZIP code 59823, the nearest ZIP area.
Nearby and next
- Montana climateThe statewide normals and every place in the state
- Seeley Lake, MT24 miles from this station, 41.7°F a year
- Ovando, MT24 miles from this station, 38.9°F a year
- Drummond, MT25 miles from this station, 43.0°F a year
- Missoula, MT25 miles from this station, 45.2°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made