Darby, MT Climate: Temperature & Rain by Month
Pulled from NOAA NCEI 1991–2020 normals →: climate measurements used in PlainClimate's documented score
30-year climate normals (1991-2020) from Darby's primary NOAA station, DARBY.
The climate verdict for Darby
Dryness leads the climate profile for Darby, Montana, with 15.1 inches of precipitation a year. NOAA records an annual average of 45°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.
- 45°F
- annual average temperature (NOAA normal)
- 40/100
- comfort score, above 6% of station-mapped location scores
- 15.1"
- yearly precipitation total
- 122 days
- frost-free days per growing season
Darby: NOAA 1991-2020 normals describe a typical year, not a forecast. Method: /methodology.
Normals record plate
Sheet USC00242221 · Darby, MT 45°F mean · 15.1" precip
TEMP-COOL · RANK-COOL · PHOTO-FINISH · PRCP-DRY · SWING-MID · COMF-LOW · LOAD-HEAT · STN-1 · BOOK-FULL
- TEMP-COOL 45°F
- RANK-COOL #1,166
- PHOTO-FINISH ≈ Kamas
- PRCP-DRY 15.1"
- SWING-MID 40°F
- COMF-LOW 40/100
- LOAD-HEAT 7,589 HDD
- STN-1 USC00242221
- BOOK-FULL 6/6 fields
Nearest mean-temperature peer: Kamas, 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.
- Darby (this station) 45°F
- Cold Loa, UT 45°F
- Hot Manila, UT 45°F
- Near Kamas, UT 45°F
- Near Great Sand Dune…, CO 45°F
Darby 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 · Darby
Darby: 20/100 · grade F
Darby publishes 4 of 6 Living Index dimensions (NOAA annual/seasonal normals · NOAA daily multivariate normals); 2 missing weights rescale to 100.
PlainClimate-derived for Darby, not an official NOAA rating. Rankings still use Comfort Score 40/100 (separate formula). Breakpoints and limits.
| Dimension | Station value | Score |
|---|---|---|
| Precipitation balance | 15.1 in · 19.9 from 35 in | 29/100 · F |
| Normal heat + freeze calendar | 188 calendar days | 21/100 · F |
| Annual temperature balance | 44.6°F · 22.9° from 67.5°F | 18/100 · F |
| Frost-free season | 122 days/year | 8/100 · F |
Darby · 2026-08-04 · NOAA NCEI Climate Normals · method · Comfort Score method.
Darby is a continental Köppen climate: Dfb
Coldest-month mean 25.7°F and warmest-month mean 65.7°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
- 65.7°F
- Coldest month
- 25.7°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 Darby sits across the climate record
Three NOAA fields for Darby's primary station, temperature, precipitation, and seasonal swing, are ranked against every station-mapped normal that carries the same field.
- Annual temperature
- Cooler than 83%
- Among 6,861 stations, Darby sits in the cooler third of annual means.
- Annual precipitation
- Drier than 82%
- Darby's annual total ranks in the drier third of 6,352 measured normals.
- Seasonal temperature swing
- 36th percentile swing
- Typical seasonal amplitude versus 6,861 complete station-years.
How Darby compares across U.S. station-mapped locations
Darby'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
Monthly Temperatures
Average daily high and low temperatures by month
| Month | Avg High | Avg Low | Mean | Precip | Freeze Days | 90°F+ Days |
|---|---|---|---|---|---|---|
| January | 34°F (1°C) | 19°F (-7°C) | 27°F (-3°C) | 1.1" | 28.0 | 0.0 |
| February | 38°F (3°C) | 21°F (-6°C) | 30°F (-1°C) | 0.9" | 25.2 | 0.0 |
| March | 47°F (8°C) | 27°F (-3°C) | 37°F (3°C) | 0.8" | 24.1 | 0.0 |
| April | 54°F (12°C) | 31°F (0°C) | 43°F (6°C) | 1.0" | 15.7 | 0.0 |
| May | 64°F (18°C) | 39°F (4°C) | 52°F (11°C) | 1.6" | 4.7 | 0.3 |
| June | 72°F (22°C) | 45°F (7°C) | 58°F (14°C) | 2.1" | 0.4 | 1.9 |
| July | 82°F (28°C) | 50°F (10°C) | 66°F (19°C) | 1.1" | 0.0 | 10.4 |
| August | 81°F (27°C) | 48°F (9°C) | 64°F (18°C) | 0.9" | 0.1 | 8.0 |
| September | 71°F (22°C) | 42°F (5°C) | 56°F (14°C) | 1.2" | 2.7 | 1.3 |
| October | 57°F (14°C) | 33°F (0°C) | 45°F (7°C) | 1.5" | 13.6 | 0.1 |
| November | 42°F (5°C) | 25°F (-4°C) | 33°F (1°C) | 1.6" | 24.1 | 0.0 |
| December | 32°F (0°C) | 19°F (-7°C) | 26°F (-4°C) | 1.3" | 28.4 | 0.0 |
The year, day by day
Summer here tops out rather than builds: the warmest normal high is 85°F around July 27, short of 90°F on every date, while 188 dates carry a normal low at or below freezing, the coldest 18°F near December 24.
The freezing stretch
The normal low stays at or below 32°F into April 22, then returns to freezing around October 18, covering 188 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 May 31, when 34% of years recorded at least a hundredth of an inch. The driest is July 27 at 17%. Summed across the calendar, that is about 88 wet dates a year.
The widest day
August 1 carries the biggest normal gap between afternoon and dawn, 34°F between the normal high and the normal low.
Look up any date
Any date's 1991–2020 normal for Darby.
Where Darby Stands Nationally
Freezing is routine here by normals standards — the normal low reaches 32°F or colder on about 188 nights a year, more than most ranked stations.
A drier-than-most normal water year — around 15 inches, below what four out of five ranked stations collect.
Darby earns 2 nationally notable standings (outer quintiles) against 6,860 NOAA 1991–2020 normals stations; only those extremes render.
Monthly Precipitation
Average monthly rainfall
8.4 days with precipitation
5.6 days with precipitation
6.4 days with precipitation
6.9 days with precipitation
9.2 days with precipitation
9.6 days with precipitation
5.6 days with precipitation
5.6 days with precipitation
6.1 days with precipitation
8.3 days with precipitation
7.9 days with precipitation
7.7 days with precipitation
Darby spreads its precipitation across the year
Neither half of the year dominates here: June through August take 27% of the annual total and December through February 21%, with neither reaching the 35% that would mark a distinct wet season. Darby has no dry season to plan around, though it does carry a 40°F seasonal spread.
The gap between the wettest and driest month still matters: June averages 2.1" and March 0.8". The three wettest months together take 35% 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.
Darby is dry, and what does fall arrives gently
Only about 87 days a year record measurable precipitation here, 24% of the calendar, and they carry 15.1" between them. At roughly 0.17 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 February at about 6.
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.
Frost Dates & Growing Season
First Fall Freeze
September 23
50% probability date
Last Spring Freeze
May 24
50% probability date
Growing Season
122 days
Heating & Cooling Degree Days
Annual totals indicate energy demand for heating and cooling
Heating Degree Days
7,589
Higher = more heating needed
Cooling Degree Days
178
Higher = more cooling needed
Warmest Month
July
Coldest Month
December
Nationwide similar cities
Other rankable U.S. places outside MT closest to Darby 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 (45°F here).
- Bath, ME 45°F · 0.0°F off
- Corning, NY 45°F · 0.0°F off
- Jackpot, NV 45°F · 0.0°F off
- Kamas, UT 45°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
Data-derived climate profile
How Darby's climate pattern fits together
heating led · dry · mid swing
Darby's energy balance leans toward cold weather: 7,589 annual heating degree days against 178 for cooling. Its 40.0°F seasonal range still makes the monthly rows more useful than the annual average alone.
Only about 122 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 December mark the typical warm and cold ends of the calendar in Darby's middle-range seasonal profile. The measured spread is 40.0°F. The annual average is 45°F. Neither the annual mean nor one extreme month represents the full calendar on its own.
Darby's cold-season load does not imply a wet climate. Annual precipitation is 15.1 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.
These labels group NOAA 1991-2020 normals from Darby's primary station, so the winter figures are a thirty-year average and not a floor: a single hard season can run well below them. Treat each band as a descriptive range for Darby, not an official NOAA class or a year-ahead forecast.
Questions about Darby's climate
How much rain does Darby get? ▼
How cold does Darby get in winter? ▼
How much energy does heating and cooling require in Darby? ▼
Data Sources
Data source: NOAA U.S. Climate Normals v1.0.1 (1991-2020). All figures on this page are from Darby's primary station: DARBY (USC00242221). 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 an incorporated place (GEOID 3019300). Match rule for Darby: 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 Darby 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.