Sun Rvr, 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 Sun Rvr's primary NOAA station, SUN RVR 4 S.
The climate verdict for Sun Rvr
Dryness leads the climate profile for Sun Rvr, Montana, with 13.3 inches of precipitation a year. NOAA records an annual average of 44°F. At 40/100 (moderate) the climate comfort score falls in the bottom third of the station-mapped U.S. score corpus, exceeding only 6% of scores.
- 44°F
- yearly average temperature, NOAA normal
- 40/100
- comfort score, above 6% of station-mapped location scores
- 13.3"
- precipitation, annual total
- 100 days
- frost-free days per growing season
Sun Rvr: NOAA 1991-2020 normals describe a typical year, not a forecast. Method: /methodology.
Normals record plate
Sheet USC00248021 · Sun Rvr, MT 44°F mean · 13.3" precip
TEMP-COOL · RANK-COOL · PHOTO-FINISH · PRCP-DRY · SWING-MID · COMF-LOW · LOAD-HEAT · STN-1 · BOOK-FULL
- TEMP-COOL 44°F
- RANK-COOL #961
- PHOTO-FINISH ≈ Park City
- PRCP-DRY 13.3"
- SWING-MID 41°F
- COMF-LOW 40/100
- LOAD-HEAT 7,940 HDD
- STN-1 USC00248021
- BOOK-FULL 6/6 fields
Nearest mean-temperature peer: Park City, UT (+ 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.
- Sun Rvr (this station) 44°F
- Hot Hayden, CO 44°F
- Near Park City, UT 44°F
- Near Rowe, MA 44°F
- Near E Jewett, NY 44°F
Sun Rvr 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 · Sun Rvr
Sun Rvr: 13/100 · grade F
Sun Rvr publishes 4 of 6 Living Index dimensions (NOAA annual/seasonal normals · NOAA daily multivariate normals); 2 missing weights rescale to 100.
PlainClimate-derived for Sun Rvr, not an official NOAA rating. Rankings still use Comfort Score 40/100 (separate formula). Breakpoints and limits.
| Dimension | Station value | Score |
|---|---|---|
| Precipitation balance | 13.3 in · 21.7 from 35 in | 23/100 · F |
| Annual temperature balance | 43.6°F · 23.9° from 67.5°F | 15/100 · F |
| Normal heat + freeze calendar | 205 calendar days | 11/100 · F |
| Frost-free season | 100 days/year | 0/100 · F |
Sun Rvr · 2026-08-04 · NOAA NCEI Climate Normals · method · Comfort Score method.
Sun Rvr's normals sit in a dry climate class: BSk
Precipitation is low relative to temperature but above true desert thresholds: cold semi-arid steppe (BSk). Class BSk is the Peel et al. (2007) label for this station's monthly mean temperature and precipitation normals: dry (arid or semi-arid), specifically cold semi-arid steppe.
- Köppen code
- BSk
- Group
- Dry (arid or semi-arid)
- Warmest month
- 65.7°F
- Coldest month
- 25.1°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 Sun Rvr sits across the climate record
Three NOAA fields for Sun Rvr's primary station, temperature, precipitation, and seasonal swing, are ranked against every station-mapped normal that carries the same field.
- Annual temperature
- Cooler than 86%
- Among 6,861 stations, Sun Rvr sits in the cooler third of annual means.
- Annual precipitation
- Drier than 87%
- Sun Rvr's annual total ranks in the drier third of 6,352 measured normals.
- Seasonal temperature swing
- 38th percentile swing
- Typical seasonal amplitude versus 6,861 complete station-years.
How Sun Rvr compares across U.S. station-mapped locations
Sun Rvr's comfort score vs. all station-mapped locations
PlainClimate composite comfort index (1–100), NOAA 1991–2020 normals
40 6th percentile score exceeds 6% 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%). Below this entry.
- 40–50: 1,113 station-mapped locations (18%). This entry sits in this band.
- 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
Sun Rvr's measured station temperature trend
MethodologyAcross 46 complete annual observations from 1955 to 2020, SUN RVR 4 S warmed at a fitted rate of 0.21°C per decade. The line shows the fitted change relative to its first year, not raw year-to-year temperatures or a forecast.
- Sun Rvr primary station fitted change +0.21 °C/decade
Monthly Temperatures
Average daily high and low temperatures by month
| Month | Avg High | Avg Low | Mean | Precip | Freeze Days | 90°F+ Days |
|---|---|---|---|---|---|---|
| January | 38°F (3°C) | 13°F (-11°C) | 25°F (-4°C) | 0.4" | 26.1 | 0.0 |
| February | 39°F (4°C) | 13°F (-11°C) | 26°F (-3°C) | 0.5" | 24.7 | 0.0 |
| March | 47°F (8°C) | 20°F (-7°C) | 33°F (1°C) | 0.6" | 24.5 | 0.0 |
| April | 56°F (13°C) | 28°F (-2°C) | 42°F (6°C) | 1.7" | 18.6 | 0.0 |
| May | 65°F (18°C) | 36°F (2°C) | 51°F (10°C) | 2.2" | 7.8 | 0.1 |
| June | 73°F (23°C) | 44°F (6°C) | 58°F (15°C) | 2.7" | 0.4 | 1.2 |
| July | 83°F (29°C) | 48°F (9°C) | 66°F (19°C) | 1.1" | 0.0 | 8.4 |
| August | 82°F (28°C) | 47°F (8°C) | 64°F (18°C) | 1.0" | 0.2 | 6.9 |
| September | 72°F (22°C) | 40°F (4°C) | 56°F (13°C) | 1.3" | 3.6 | 1.3 |
| October | 58°F (14°C) | 31°F (-1°C) | 44°F (7°C) | 0.9" | 15.1 | 0.0 |
| November | 45°F (7°C) | 21°F (-6°C) | 33°F (1°C) | 0.6" | 22.4 | 0.0 |
| December | 37°F (3°C) | 14°F (-10°C) | 25°F (-4°C) | 0.4" | 26.7 | 0.0 |
The year, day by day
Summer here tops out rather than builds: the warmest normal high is 86°F around July 27, short of 90°F on every date, while 205 dates carry a normal low at or below freezing, the coldest 12°F near January 1.
The freezing stretch
The normal low stays at or below 32°F into May 4, then returns to freezing around October 13, covering 205 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 6, when 28% of years recorded at least a hundredth of an inch. The driest is December 3 at 11%. Summed across the calendar, that is about 63 wet dates a year.
The widest day
July 27 carries the biggest normal gap between afternoon and dawn, 37°F between the normal high and the normal low.
Look up any date
Any date's 1991–2020 normal for Sun Rvr.
Where Sun Rvr Stands Nationally
Winters bite deep and often: the normal nightly low dips to freezing or below on around 205 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 37°F, sharper than nine in ten ranked stations see.
Sun Rvr earns 2 nationally notable standings (outer quintiles) against 6,860 NOAA 1991–2020 normals stations; only those extremes render.
Monthly Precipitation
Average monthly rainfall
3.8 days with precipitation
4.7 days with precipitation
5.2 days with precipitation
7.4 days with precipitation
7.1 days with precipitation
8.4 days with precipitation
4.3 days with precipitation
4.0 days with precipitation
4.6 days with precipitation
4.6 days with precipitation
4.2 days with precipitation
3.5 days with precipitation
Sun Rvr runs a summer-peaked wet season
36% of Sun Rvr's yearly precipitation falls in June, July and August alone, against the 25% an evenly spread year would give those three months. The wettest month is June at 2.7", on a 40.6°F seasonal spread. Warm-season convection and, across the Southwest, the North American monsoon produce this shape: rain arrives in short heavy bursts during the hottest part of the year rather than as long cool-season soaking.
- Wettest three months: June, May, April, taking 49% of the annual total between them.
- Driest month: December at 0.4".
- Winter share: 10% falls in December, January and February.
Shares are computed from this station's own 1991-2020 monthly precipitation normals. A summer-peaked label means the June-August share reaches 35%; it describes timing across an average year, not any single season, and says nothing about how heavy an individual storm can be.
How Sun Rvr's precipitation splits across the calendar
About 62 days a year record measurable precipitation here, carrying 13.3" between them, or roughly 0.22 inches on a typical wet day. That sits in the middle band: neither the many-light-days pattern of the Pacific Northwest and the Great Lakes, nor the few-heavy-events pattern of the Gulf and the desert Southwest.
A wet day is one recording at least 0.01 inches. These are 1991-2020 normals: they describe an average year and say nothing about the heaviest single storm on record.
Frost Dates & Growing Season
First Fall Freeze
September 10
50% probability date
Last Spring Freeze
June 2
50% probability date
Growing Season
100 days
Heating & Cooling Degree Days
Annual totals indicate energy demand for heating and cooling
Heating Degree Days
7,940
Higher = more heating needed
Cooling Degree Days
178
Higher = more cooling needed
Warmest Month
July
Coldest Month
January
Nationwide similar cities
Other rankable U.S. places outside MT closest to Sun Rvr 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 (44°F here).
- Andover, MN 44°F · 0.0°F off
- Clearmont, WY 44°F · 0.0°F off
- Conde, SD 44°F · 0.0°F off
- Crestone, CO 44°F · 0.0°F off
Closest by annual precipitation
Nearest out-of-state peers by annual precipitation (13.3" here), excluding temperature-peer places.
- Carrizozo, NM 13.3" · 0.0" off
- Salina, UT 13.3" · 0.0" off
- La Junta, CO 13.4" · 0.0" off
- Monahans, TX 13.4" · 0.0" off
Scarce-water calendar
Where Sun Rvr's limited precipitation lands
heating led · dry · mid swing
Sun Rvr's energy balance leans toward cold weather: 7,940 annual heating degree days against 178 for cooling. Its 40.6°F seasonal range still makes the monthly rows more useful than the annual average alone.
Only about 100 days are frost-free in a normal year. That short interval is consistent with the cold-season signal, but the measure does not predict the exact first or last freeze in any one year.
July and January mark the typical warm and cold ends of the calendar in Sun Rvr's middle-range seasonal profile. The measured spread is 40.6°F. The annual average is 44°F. Neither the annual mean nor one extreme month represents the full calendar on its own.
Sun Rvr's cold-season load does not imply a wet climate. Annual precipitation is 13.3 inches, which places the station in PlainClimate's dry range. Snowfall is not added to the interpretation because its annual value is missing. The snowfall and rainfall fields should be read separately rather than inferred from temperature.
Sun Rvr wettest normal
June
June concentrates the scarce annual total (13.3 inches).
Sun Rvr driest normal
December
December is typically driest; arid stations are defined by when water is absent, not by a four-season grid.
Questions about Sun Rvr's climate
How dry is Sun Rvr? ▼
How cold does Sun Rvr get in winter? ▼
How much energy does heating and cooling require in Sun Rvr? ▼
Data Sources
Data source: NOAA U.S. Climate Normals v1.0.1 (1991-2020). All figures on this page are from Sun Rvr's primary station: SUN RVR 4 S (USC00248021). For informational purposes only.
Place identity: U.S. Census Bureau 2024 Gazetteer places. The conservative exact name-and-state crosswalk finds no Census place match, so PlainClimate treats this as a station-mapped location and does not claim it is a municipality. No exact Gazetteer row for Sun Rvr; facility counts that depend on place identity are therefore an upper bound, not a municipal census.
On this page every temperature, precipitation, and derived score for Sun Rvr 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.