Lewistown, MT Climate: Temperature & Rain by Month
Annual temperature and rainfall from NOAA NCEI's 1991–2020 normals →; comfort score computed by PlainClimate
30-year climate normals (1991-2020) from Lewistown's primary NOAA station, LEWISTOWN 42 WSW - 4 stations mapped to the area.
The climate verdict for Lewistown
Dryness leads the climate profile for Lewistown, Montana, with 16.8 inches of precipitation a year. NOAA records an annual average of 41°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.
- 41°F
- average temperature, NOAA 1991-2020 normal
- 40/100
- comfort score, above 6% of station-mapped location scores
- 16.8"
- precipitation, annual total
- 81 days
- growing season, frost-free days
Lewistown: NOAA 1991-2020 normals describe a typical year, not a forecast. Method: /methodology.
Normals record plate
Sheet USW00004140 · Lewistown, MT 41°F mean · 16.8" precip
TEMP-COOL · RANK-COOL · PHOTO-FINISH · PRCP-DRY · SWING-MID · COMF-LOW · LOAD-HEAT · STN-MULTI · BOOK-FULL
- TEMP-COOL 41°F
- RANK-COOL #412
- PHOTO-FINISH ≈ Dubois
- PRCP-DRY 16.8"
- SWING-MID 37°F
- COMF-LOW 40/100
- LOAD-HEAT 8,917 HDD
- STN-MULTI USW00004140
- BOOK-FULL 6/6 fields
Nearest mean-temperature peer: Dubois, WY ( -0.1 °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.
- Lewistown (this station) 41°F
- Cold Dubois, WY 41°F
- Hot Wilsall, MT 41°F
- Near Seneca, OR 41°F
- Near Ouzinkie, AK 41°F
Lewistown 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 · Lewistown
Lewistown: 10/100 · grade F
Lewistown publishes 4 of 6 Living Index dimensions (NOAA annual/seasonal normals · NOAA daily multivariate normals); 2 missing weights rescale to 100.
PlainClimate-derived for Lewistown, not an official NOAA rating. Rankings still use Comfort Score 40/100 (separate formula). Breakpoints and limits.
| Dimension | Station value | Score |
|---|---|---|
| Precipitation balance | 16.8 in · 18.2 from 35 in | 35/100 · F |
| Annual temperature balance | 40.6°F · 26.9° from 67.5°F | 6/100 · F |
| Normal heat + freeze calendar | 227 calendar days | 3/100 · F |
| Frost-free season | 81 days/year | 0/100 · F |
Lewistown · 2026-08-04 · NOAA NCEI Climate Normals · method · Comfort Score method.
Lewistown is a continental Köppen climate: Dfb
Coldest-month mean 24.0°F and warmest-month mean 60.9°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
- 60.9°F
- Coldest month
- 24.0°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 Lewistown sits across the climate record
Three NOAA fields for Lewistown's primary station, temperature, precipitation, and seasonal swing, are ranked against every station-mapped normal that carries the same field.
- Annual temperature
- Cooler than 94%
- Among 6,861 stations, Lewistown sits in the cooler third of annual means.
- Annual precipitation
- Drier than 78%
- Lewistown's annual total ranks in the drier third of 6,352 measured normals.
- Seasonal temperature swing
- Narrower than 77%
- Warmest-to-coldest month gap for Lewistown is compact versus 6,861 complete station-years.
How Lewistown compares across U.S. station-mapped locations
Lewistown'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 | Snow | Freeze Days | 90°F+ Days |
|---|---|---|---|---|---|---|---|
| January | 37°F (3°C) | 13°F (-10°C) | 25°F (-4°C) | 0.6" | N/A | 28.7 | 0.0 |
| February | 36°F (2°C) | 12°F (-11°C) | 24°F (-4°C) | 0.8" | N/A | 26.5 | 0.0 |
| March | 44°F (6°C) | 20°F (-7°C) | 32°F (0°C) | 0.9" | N/A | 28.1 | 0.0 |
| April | 50°F (10°C) | 25°F (-4°C) | 37°F (3°C) | 1.6" | N/A | 26.2 | 0.0 |
| May | 60°F (15°C) | 33°F (1°C) | 46°F (8°C) | 2.8" | N/A | 15.0 | 0.0 |
| June | 67°F (20°C) | 40°F (4°C) | 54°F (12°C) | 3.1" | N/A | 2.8 | 0.3 |
| July | 78°F (25°C) | 44°F (7°C) | 61°F (16°C) | 1.7" | N/A | 0.4 | 1.6 |
| August | 77°F (25°C) | 44°F (7°C) | 61°F (16°C) | 1.4" | N/A | 1.3 | 1.6 |
| September | 69°F (20°C) | 36°F (2°C) | 52°F (11°C) | 1.3" | N/A | 8.4 | 0.2 |
| October | 53°F (12°C) | 28°F (-2°C) | 41°F (5°C) | 1.3" | N/A | 21.0 | 0.0 |
| November | 42°F (6°C) | 20°F (-6°C) | 31°F (0°C) | 0.7" | N/A | 24.4 | 0.0 |
| December | 35°F (2°C) | 13°F (-10°C) | 24°F (-4°C) | 0.6" | N/A | 28.7 | 0.0 |
The year, day by day
Summer here tops out rather than builds: the warmest normal high is 80°F around July 27, short of 90°F on every date, while 227 dates carry a normal low at or below freezing, the coldest 11°F near February 11.
The freezing stretch
The normal low stays at or below 32°F into May 13, then returns to freezing around September 30, covering 227 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 17, when 49% of years recorded at least a hundredth of an inch. The driest is September 3 at 24%. Summed across the calendar, that is about 120 wet dates a year.
The widest day
September 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 Lewistown.
Where Lewistown Stands Nationally
Winters bite deep and often: the normal nightly low dips to freezing or below on around 227 nights a year, placing this among the most frost-prone tenth of ranked stations.
Daily temperature swings run wider than most of the country, peaking near 34°F between the normal high and low.
Lewistown 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
8.5 days with precipitation
10.3 days with precipitation
9.5 days with precipitation
13.3 days with precipitation
15.2 days with precipitation
12.3 days with precipitation
9.4 days with precipitation
9.0 days with precipitation
7.1 days with precipitation
8.8 days with precipitation
7.7 days with precipitation
9.3 days with precipitation
Lewistown runs a summer-peaked wet season
37% of Lewistown'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 3.1", on a 36.9°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, July, taking 45% of the annual total between them.
- Driest month: December at 0.6".
- Winter share: 12% 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.
Rain reaches Lewistown in small, frequent amounts
Lewistown records about 120 days with measurable precipitation a year and 16.8" in total, which works out to roughly 0.14 inches on an average wet day. Precipitation on 33% of all days, arriving that lightly, is the damp many-grey-days pattern rather than the storm-driven one.
Places in this band read as wetter than their annual totals suggest, because what people notice is the number of overcast days, not the depth in the gauge.
- Most wet days: May, about 15 of them.
- Fewest: September, about 7.
- Average depth per wet day: 0.14 inches.
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 4
50% probability date
Last Spring Freeze
June 15
50% probability date
Growing Season
81 days
Heating & Cooling Degree Days
Annual totals indicate energy demand for heating and cooling
Heating Degree Days
8,917
Higher = more heating needed
Cooling Degree Days
46
Higher = more cooling needed
Warmest Month
July
Coldest Month
February
Nationwide similar cities
Other rankable U.S. places outside MT closest to Lewistown 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 (41°F here).
- Aitkin, MN 41°F · 0.0°F off
- Aspen, CO 41°F · 0.0°F off
- Centennial, WY 41°F · 0.0°F off
- Chatham, MI 41°F · 0.0°F off
Closest by annual precipitation
Nearest out-of-state peers by annual precipitation (16.8" here), excluding temperature-peer places.
- Chugwater, WY 16.8" · 0.0" off
- Minot, ND 16.7" · 0.1" off
- Cantwell, AK 16.8" · 0.1" off
- Bushnell, NE 16.7" · 0.1" off
Data-derived climate profile
How Lewistown's climate pattern fits together
heating led · dry · mid swing
Lewistown's energy balance leans toward cold weather: 8,917 annual heating degree days against 46 for cooling. Its 36.9°F seasonal range still makes the monthly rows more useful than the annual average alone.
Only about 81 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 February mark the typical warm and cold ends of the calendar in Lewistown's middle-range seasonal profile. The measured spread is 36.9°F. The annual average is 41°F. Neither the annual mean nor one extreme month represents the full calendar on its own.
Lewistown's cold-season load does not imply a wet climate. Annual precipitation is 16.8 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 Lewistown'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 Lewistown, not an official NOAA class or a year-ahead forecast.
Questions about Lewistown's climate
How much rain does Lewistown get? ▼
How cold does Lewistown get in winter? ▼
How much energy does heating and cooling require in Lewistown? ▼
Data Sources
Data source: NOAA U.S. Climate Normals v1.0.1 (1991-2020). All figures on this page are from Lewistown's primary station: LEWISTOWN 42 WSW (USW00004140). 4 NOAA stations are mapped to the Lewistown area; the primary station's record is used for consistency. 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 3043375). Match rule for Lewistown: 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 Lewistown 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.