Potomac, MT Climate: Temperature & Rain by Month
Average temperature and precipitation from NOAA NCEI 1991–2020 normals →, with a derived climate comfort score
30-year climate normals (1991-2020) from Potomac's primary NOAA station, POTOMAC.
The climate verdict for Potomac
Dryness leads the climate profile for Potomac, Montana, with 15.1 inches of precipitation a year. NOAA records an annual average of 39°F. At 35/100 (below average) the climate comfort score falls in the bottom third of the station-mapped U.S. score corpus, exceeding only 4% of scores.
- 39°F
- average temperature, NOAA 1991-2020 normal
- 35/100
- comfort score, above 4% of station-mapped location scores
- 15.1"
- annual precipitation · 52" snow
Potomac: NOAA 1991-2020 normals describe a typical year, not a forecast. Method: /methodology.
Normals record plate
Sheet USC00246685 · Potomac, MT 39°F mean · 15.1" precip
TEMP-COLD · RANK-COOL · PHOTO-FINISH · PRCP-DRY · SWING-MID · COMF-LOW · LOAD-HEAT · STN-1 · BOOK-FULL
- TEMP-COLD 39°F
- RANK-COOL #274
- PHOTO-FINISH ≈ Sula
- PRCP-DRY 15.1"
- SWING-MID 42°F
- COMF-LOW 35/100
- LOAD-HEAT 9,385 HDD
- STN-1 USC00246685
- BOOK-FULL 6/6 fields
Nearest mean-temperature peer: Sula, MT (+ 0 °F mean)
Instrument codes from this station's NOAA 1991–2020 normals, mean temperature, corpus warmth rank, photo-finish peer station, precipitation band, seasonal swing, comfort composite, degree-day load, and field book, not a livability rating.
Mean-temperature neighbourhood
Nationwide NOAA normal poles and nearest peers, not a reprint of every MT station list.
- Potomac (this station) 39°F
- Cold Woodruff, UT 39°F
- Hot Randolph, UT 39°F
- Near Sula, MT 39°F
- Near Tetonia, ID 39°F
Potomac sits in Montana, the #6 coldest U.S. state at 43.4°F statewide annual average - see all 50 coldest states ranked by NOAA normals
Climate Living Index · Potomac
Potomac: 9/100 · grade F
Potomac publishes 4 of 6 Living Index dimensions (NOAA annual/seasonal normals · NOAA daily multivariate normals); 2 missing weights rescale to 100.
PlainClimate-derived for Potomac, not an official NOAA rating. Rankings still use Comfort Score 35/100 (separate formula). Breakpoints and limits.
| Dimension | Station value | Score |
|---|---|---|
| Precipitation balance | 15.1 in · 19.9 from 35 in | 29/100 · F |
| Snowfall burden | 51.8 inches/year | 20/100 · F |
| Annual temperature balance | 39.3°F · 28.2° from 67.5°F | 3/100 · F |
| Normal heat + freeze calendar | 249 calendar days | 0/100 · F |
Potomac · 2026-08-04 · NOAA NCEI Climate Normals · method · Comfort Score method.
Potomac is a continental Köppen climate: Dfb
Coldest-month mean 18.9°F and warmest-month mean 61.3°F place this station in continental, no dry season, warm summer climates (Dfb). Class Dfb is the Peel et al. (2007) label for this station's monthly mean temperature and precipitation normals: continental, specifically continental, no dry season, warm summer.
- Köppen code
- Dfb
- Group
- Continental
- Warmest month
- 61.3°F
- Coldest month
- 18.9°F
Source: official public datasets monthly normals (1991–2020) at the city’s primary station. This is a station classification, not a mapped regional consensus.
National standing · heating-led station
Where Potomac sits across the climate record
Three NOAA fields for Potomac's primary station, temperature, precipitation, and seasonal swing, are ranked against every station-mapped normal that carries the same field.
- Annual temperature
- Cooler than 96%
- Among 6,861 stations, Potomac sits in the cooler third of annual means.
- Annual precipitation
- Drier than 82%
- Potomac's annual total ranks in the drier third of 6,352 measured normals.
- Seasonal temperature swing
- 46th percentile swing
- Typical seasonal amplitude versus 6,861 complete station-years.
How Potomac compares across U.S. station-mapped locations
Potomac's comfort score vs. all station-mapped locations
PlainClimate composite comfort index (1–100), NOAA 1991–2020 normals
35 4th percentile score exceeds 4% of 6,189 station-mapped location scores
- 0–10: 0 station-mapped locations (0%). Below this entry.
- 10–20: 0 station-mapped locations (0%). Below this entry.
- 20–30: 96 station-mapped locations (2%). Below this entry.
- 30–40: 280 station-mapped locations (5%). This entry sits in this band.
- 40–50: 1,113 station-mapped locations (18%). Above this entry.
- 50–60: 1,329 station-mapped locations (21%). Above this entry.
- 60–70: 1,236 station-mapped locations (20%). Above this entry.
- 70–80: 650 station-mapped locations (11%). Above this entry.
- 80–90: 921 station-mapped locations (15%). Above this entry.
- 90–100: 564 station-mapped locations (9%). Above this entry.
Source NOAA U.S. Climate Normals, PlainClimate comfort index · 1991–2020
Monthly Temperatures
Average daily high and low temperatures by month
| Month | Avg High | Avg Low | Mean | Precip | Snow | Freeze Days | 90°F+ Days |
|---|---|---|---|---|---|---|---|
| January | 30°F (-1°C) | 8°F (-13°C) | 19°F (-7°C) | 1.4" | 15.5" | 30.7 | 0.0 |
| February | 35°F (2°C) | 9°F (-13°C) | 22°F (-6°C) | 1.0" | 7.2" | 27.8 | 0.0 |
| March | 46°F (8°C) | 18°F (-8°C) | 32°F (0°C) | 0.8" | 4.6" | 30.5 | 0.0 |
| April | 54°F (12°C) | 24°F (-5°C) | 39°F (4°C) | 1.1" | 1.3" | 27.0 | 0.0 |
| May | 64°F (18°C) | 30°F (-1°C) | 47°F (8°C) | 1.9" | 0.4" | 17.4 | 0.1 |
| June | 71°F (22°C) | 38°F (3°C) | 55°F (13°C) | 2.2" | 0.0" | 5.0 | 0.7 |
| July | 82°F (28°C) | 41°F (5°C) | 61°F (16°C) | 0.8" | 0.0" | 1.5 | 7.0 |
| August | 82°F (28°C) | 39°F (4°C) | 60°F (16°C) | 0.6" | 0.0" | 4.0 | 7.2 |
| September | 71°F (22°C) | 32°F (0°C) | 52°F (11°C) | 0.9" | 0.2" | 16.3 | 1.4 |
| October | 55°F (13°C) | 23°F (-5°C) | 39°F (4°C) | 1.5" | 1.9" | 26.9 | 0.0 |
| November | 39°F (4°C) | 16°F (-9°C) | 28°F (-2°C) | 1.6" | 7.4" | 28.7 | 0.0 |
| December | 29°F (-2°C) | 9°F (-13°C) | 19°F (-7°C) | 1.4" | 13.3" | 30.9 | 0.0 |
The year, day by day
Summer here tops out rather than builds: the warmest normal high is 85°F around July 28, short of 90°F on every date, while 249 dates carry a normal low at or below freezing, the coldest 7°F near December 26.
The freezing stretch
The normal low stays at or below 32°F into May 21, then returns to freezing around September 16, covering 249 dates in all.
Derived from the normal daily minimum. This is a different measure from the 50%-probability frost dates shown elsewhere on this page, which come from NOAA’s frost product.
Where the wet dates fall
The likeliest wet date is June 8, when 33% of years recorded at least a hundredth of an inch. The driest is August 12 at 13%. Summed across the calendar, that is about 81 wet dates a year.
The widest day
August 2 carries the biggest normal gap between afternoon and dawn, 44°F between the normal high and the normal low.
Look up any date
Any date's 1991–2020 normal for Potomac.
Where Potomac Stands Nationally
Winters bite deep and often: the normal nightly low dips to freezing or below on around 249 nights a year, placing this among the most frost-prone tenth of ranked stations.
Day-to-night contrast is extreme by national standards — the widest normal daily swing reaches about 44°F, sharper than nine in ten ranked stations see.
Potomac earns 2 nationally notable standings (outer quintiles) against 6,860 NOAA 1991–2020 normals stations; only those extremes render.
Monthly Precipitation
Average monthly rainfall and snowfall
Snow: 15.5"
8.0 days with precipitation
Snow: 7.2"
5.9 days with precipitation
Snow: 4.6"
5.6 days with precipitation
Snow: 1.3"
5.6 days with precipitation
Snow: 0.4"
8.0 days with precipitation
9.5 days with precipitation
5.4 days with precipitation
3.9 days with precipitation
Snow: 0.2"
5.4 days with precipitation
Snow: 1.9"
7.0 days with precipitation
Snow: 7.4"
8.0 days with precipitation
Snow: 13.3"
8.2 days with precipitation
Potomac spreads its precipitation across the year
Neither half of the year dominates here: June through August take 24% of the annual total and December through February 25%, with neither reaching the 35% that would mark a distinct wet season. Potomac has no dry season to plan around, though it does carry a 42.4°F seasonal spread.
The gap between the wettest and driest month still matters: June averages 2.2" and August 0.6". The three wettest months together take 37% of the year, against the 25% a perfectly flat distribution would give them.
Shares are computed from this station's own 1991-2020 monthly precipitation normals. "Spread across the year" means neither the June-August nor the December-February share reaches 35%; it describes an average year, not the variability of any single one.
Potomac is dry, and what does fall arrives gently
Only about 81 days a year record measurable precipitation here, 22% of the calendar, and they carry 15.1" between them. At roughly 0.19 inches on an average wet day, this is not the damp drizzle of a marine climate; it is an arid record in which precipitation is both uncommon and light when it appears.
The wettest month by count is June at about 10 wet days; the driest is August at about 4.
A low per-event average in a dry record is a statement about typical days only. Arid regions can still take a large share of a year's total from a single convective storm, which a normal cannot show.
A wet day is one recording at least 0.01 inches. These are 1991-2020 normals: they describe an average year, not the extremes within it.
Winter brings real snow to Potomac
Potomac averages 51.8 inches of snowfall a year, with January the snowiest month on the normals, spread across roughly 24 days that record measurable snow. That is depth accumulating on the ground, which is why it can exceed the annual precipitation figure: precipitation counts the liquid the snow melts down to, and fresh snow is mostly air.
- Annual snowfall: 51.8 inches of depth.
- Days recording measurable snow: about 24 a year.
- At a rough ten-to-one melt ratio, snow accounts for on the order of 34% of the year's precipitation.
NOAA 1991-2020 normals. The ten-to-one ratio is a convention, not a measurement: real ratios vary with temperature, so treat the share as an order of magnitude rather than an exact split.
Frost Dates & Growing Season
First Fall Freeze
N/A
50% probability date
Last Spring Freeze
N/A
50% probability date
Heating & Cooling Degree Days
Annual totals indicate energy demand for heating and cooling
Heating Degree Days
9,385
Higher = more heating needed
Cooling Degree Days
53
Higher = more cooling needed
Warmest Month
July
Coldest Month
December
Nationwide similar cities
Other rankable U.S. places outside MT closest to Potomac on two NOAA annual-normal axes (mean temperature and annual precipitation). Chip rows use distinct link sets.
Closest by average temperature
Nearest out-of-state peers by annual mean temperature (39°F here).
- Cold Bay, AK 39°F · 0.0°F off
- Cooperstown, ND 39°F · 0.0°F off
- Devils Lake, ND 39°F · 0.0°F off
- Rangeley, ME 39°F · 0.0°F off
Closest by annual precipitation
Nearest out-of-state peers by annual precipitation (15.1" here), excluding temperature-peer places.
- Bly, OR 15.1" · 0.0" off
- Guernsey, WY 15.1" · 0.0" off
- Lee Vining, CA 15.1" · 0.0" off
- Monticello, UT 15.1" · 0.0" off
Snow and freeze rhythm
When cold and snow define Potomac
heating led · dry · mid swing
Potomac's energy balance leans toward cold weather: 9,385 annual heating degree days against 53 for cooling. Its 42.4°F seasonal range still makes the monthly rows more useful than the annual average alone.
A frost-free growing-season length is not available for Potomac. That missing field is kept separate from the observed temperature and precipitation record rather than filled from a regional estimate.
-
1. Potomac coldest normal
December
Averaging 19°F (-7°C), this month sits below freezing for the month as a whole, not merely overnight.
-
2. Potomac typical freeze period
January through December
The station reports average freezing days from January through December.
-
3. Potomac snow peak
January
Potomac averages 51.8 inches of snow a year, with January the snowiest month on the normals.
Questions about Potomac's climate
How much snow does Potomac get? ▼
How cold does Potomac get in winter? ▼
How much energy does heating and cooling require in Potomac? ▼
Data Sources
Data source: NOAA U.S. Climate Normals v1.0.1 (1991-2020). All figures on this page are from Potomac's primary station: POTOMAC (USC00246685). For informational purposes only.
Place identity: U.S. Census Bureau 2024 Gazetteer places. The 2024 Census Gazetteer identifies the exact name-and-state match as a census-designated place (GEOID 3059350), not an incorporated municipality. Match rule for Potomac: exact normalized name + state only, no fuzzy expansion, so nearby differently spelled facilities stay unmatched.
On this page every temperature, precipitation, and derived score for Potomac comes from its primary NOAA station record. No figure on this page is typed in by an editor - each value is rendered from NOAA 1991-2020 U.S. Climate Normals. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. Data current as of 1991–2020 normals.