Roy, 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 Roy's primary NOAA station, ROY 8 NE.
The climate verdict for Roy
Dryness leads the climate profile for Roy, Montana, with 13.3 inches of precipitation a year. NOAA records an annual average of 45°F. At 49/100 (moderate) the climate comfort score falls in the bottom third of the station-mapped U.S. score corpus, exceeding only 18% of scores.
- 45°F
- yearly average temperature, NOAA normal
- 49/100
- comfort score, above 18% of station-mapped location scores
- 13.3"
- annual precipitation · 36" snow
- 133 days
- frost-free growing season
Roy: NOAA 1991-2020 normals describe a typical year, not a forecast. Method: /methodology.
Normals record plate
Sheet USC00247228 · Roy, MT 45°F mean · 13.3" precip
TEMP-COOL · RANK-COOL · PHOTO-FINISH · PRCP-DRY · SWING-WIDE · COMF-LOW · LOAD-HEAT · STN-1 · BOOK-FULL
- TEMP-COOL 45°F
- RANK-COOL #1,372
- PHOTO-FINISH ≈ Beloit
- PRCP-DRY 13.3"
- SWING-WIDE 48°F
- COMF-LOW 49/100
- LOAD-HEAT 7,566 HDD
- STN-1 USC00247228
- BOOK-FULL 6/6 fields
Nearest mean-temperature peer: Beloit, WI (+ 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.
- Roy (this station) 45°F
- Cold Dubois, ID 45°F
- Hot Fort Benton, MT 45°F
- Near Beloit, WI 45°F
- Near Sheridan County, WY 45°F
Roy 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 · Roy
Roy: 21/100 · grade F
Roy publishes 5 of 6 Living Index dimensions (NOAA annual/seasonal normals · NOAA daily multivariate normals); 1 missing weight rescale to 100.
PlainClimate-derived for Roy, not an official NOAA rating. Rankings still use Comfort Score 49/100 (separate formula). Breakpoints and limits.
| Dimension | Station value | Score |
|---|---|---|
| Snowfall burden | 36.3 inches/year | 32/100 · F |
| Precipitation balance | 13.3 in · 21.7 from 35 in | 22/100 · F |
| Annual temperature balance | 45.4°F · 22.1° from 67.5°F | 21/100 · F |
| Normal heat + freeze calendar | 191 calendar days | 19/100 · F |
| Frost-free season | 133 days/year | 14/100 · F |
Roy · 2026-08-04 · NOAA NCEI Climate Normals · method · Comfort Score method.
Roy'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
- 70.2°F
- Coldest month
- 22.3°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 Roy sits across the climate record
Three NOAA fields for Roy's primary station, temperature, precipitation, and seasonal swing, are ranked against every station-mapped normal that carries the same field.
- Annual temperature
- Cooler than 80%
- Among 6,861 stations, Roy sits in the cooler third of annual means.
- Annual precipitation
- Drier than 87%
- Roy's annual total ranks in the drier third of 6,352 measured normals.
- Seasonal temperature swing
- Wider than 72%
- Warmest-to-coldest month gap for Roy is large versus 6,861 complete station-years.
How Roy compares across U.S. station-mapped locations
Roy's comfort score vs. all station-mapped locations
PlainClimate composite comfort index (1–100), NOAA 1991–2020 normals
49 18th percentile score exceeds 18% 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 | Snow | Freeze Days | 90°F+ Days |
|---|---|---|---|---|---|---|---|
| January | 34°F (1°C) | 10°F (-12°C) | 22°F (-5°C) | 0.5" | 7.7" | 29.3 | 0.0 |
| February | 37°F (3°C) | 13°F (-10°C) | 25°F (-4°C) | 0.4" | 4.7" | 26.1 | 0.0 |
| March | 48°F (9°C) | 22°F (-6°C) | 35°F (2°C) | 0.5" | 6.8" | 26.1 | 0.0 |
| April | 58°F (14°C) | 30°F (-1°C) | 44°F (7°C) | 1.3" | 2.6" | 15.9 | 0.0 |
| May | 68°F (20°C) | 40°F (4°C) | 54°F (12°C) | 2.5" | 0.6" | 5.7 | 0.1 |
| June | 76°F (25°C) | 48°F (9°C) | 62°F (17°C) | 2.6" | 0.0" | 0.1 | 1.5 |
| July | 86°F (30°C) | 54°F (12°C) | 70°F (21°C) | 1.7" | 0.0" | 0.0 | 9.4 |
| August | 86°F (30°C) | 53°F (12°C) | 69°F (21°C) | 1.3" | 0.0" | 0.1 | 12.5 |
| September | 76°F (24°C) | 43°F (6°C) | 59°F (15°C) | 0.9" | 0.0" | 3.0 | 2.8 |
| October | 60°F (16°C) | 32°F (0°C) | 46°F (8°C) | 0.7" | 1.9" | 14.8 | 0.1 |
| November | 46°F (8°C) | 21°F (-6°C) | 33°F (1°C) | 0.5" | 5.5" | 26.1 | 0.0 |
| December | 36°F (2°C) | 12°F (-11°C) | 24°F (-4°C) | 0.4" | 6.5" | 29.6 | 0.0 |
The year, day by day
Summer here tops out rather than builds: the warmest normal high is 90°F around July 30, short of 90°F on every date, while 191 dates carry a normal low at or below freezing, the coldest 9°F near January 1.
The freezing stretch
The normal low stays at or below 32°F into April 24, then returns to freezing around October 17, covering 191 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 10, when 34% of years recorded at least a hundredth of an inch. The driest is December 3 at 9%. Summed across the calendar, that is about 66 wet dates a year.
The widest day
August 3 carries the biggest normal gap between afternoon and dawn, 33°F between the normal high and the normal low.
Look up any date
Any date's 1991–2020 normal for Roy.
Where Roy Stands Nationally
Freezing is routine here by normals standards — the normal low reaches 32°F or colder on about 191 nights a year, more than most ranked stations.
A drier-than-most normal water year — around 13 inches, below what four out of five ranked stations collect.
Roy 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: 7.7"
4.0 days with precipitation
Snow: 4.7"
3.1 days with precipitation
Snow: 6.8"
4.7 days with precipitation
Snow: 2.6"
5.5 days with precipitation
Snow: 0.6"
8.5 days with precipitation
10.1 days with precipitation
8.3 days with precipitation
5.2 days with precipitation
5.0 days with precipitation
Snow: 1.9"
4.3 days with precipitation
Snow: 5.5"
3.8 days with precipitation
Snow: 6.5"
3.0 days with precipitation
Roy runs a summer-peaked wet season
42% of Roy'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 2.6", on a wide 47.9°F gap between its warmest and coldest month. 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, July, taking 52% of the annual total between them.
- Driest month: February at 0.4".
- Winter share: 9% 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 Roy's precipitation splits across the calendar
About 66 days a year record measurable precipitation here, carrying 13.3" between them, or roughly 0.20 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.
Winter brings real snow to Roy
Roy averages 36.3 inches of snowfall a year, with January the snowiest month on the normals, spread across roughly 16 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: 36.3 inches of depth.
- Days recording measurable snow: about 16 a year.
- At a rough ten-to-one melt ratio, snow accounts for on the order of 27% 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
September 24
50% probability date
Last Spring Freeze
May 14
50% probability date
Growing Season
133 days
Heating & Cooling Degree Days
Annual totals indicate energy demand for heating and cooling
Heating Degree Days
7,566
Higher = more heating needed
Cooling Degree Days
449
Higher = more cooling needed
Warmest Month
July
Coldest Month
January
Nationwide similar cities
Other rankable U.S. places outside MT closest to Roy 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).
- Beloit, WI 45°F · 0.0°F off
- Deadwood, SD 45°F · 0.0°F off
- Fort Hall, ID 45°F · 0.0°F off
- Harbor Beach, MI 45°F · 0.0°F off
Closest by annual precipitation
Nearest out-of-state peers by annual precipitation (13.3" here), excluding temperature-peer places.
- Salina, UT 13.3" · 0.0" off
- Carrizozo, NM 13.3" · 0.0" off
- Emmett, ID 13.3" · 0.0" off
- La Junta, CO 13.4" · 0.0" off
Snow and freeze rhythm
When cold and snow define Roy
heating led · dry · mid swing
Roy's energy balance leans toward cold weather: 7,566 annual heating degree days against 449 for cooling. Its 47.9°F seasonal range still makes the monthly rows more useful than the annual average alone.
Only about 133 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.
-
1. Roy coldest normal
January
Averaging 22°F (-5°C), this month sits below freezing for the month as a whole, not merely overnight.
-
2. Roy typical freeze period
January through December
The station reports average freezing days from January through December.
-
3. Roy snow peak
January
Roy averages 36.3 inches of snow a year, with January the snowiest month on the normals.
Questions about Roy's climate
How much snow does Roy get? ▼
How cold does Roy get in winter? ▼
How much energy does heating and cooling require in Roy? ▼
Data Sources
Data source: NOAA U.S. Climate Normals v1.0.1 (1991-2020). All figures on this page are from Roy's primary station: ROY 8 NE (USC00247228). 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 3064675), not an incorporated municipality. Match rule for Roy: 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 Roy 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.