Lewistown, Montana climate: Normal weather by month, frost dates and records
Lewistown's normal year runs from 13°F January nights to 82°F July afternoons, with 17.2 inches of precipitation a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 6.2°C, January lows of −11°C, July highs of 28°C, 436 mm of precipitation a year.
- NOAA stationLewistown Municipal Airport
- Station IDUSW00024036
- Location47.05°N 109.46°W
- Elevation4,145 ft (1,263 m)
- Population6,204
On October 23, the normal high in Lewistown is 53°F and the normal low 28°F, and the chance of measurable rain or snow is 29%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Lewistown.
- Jan 34° 13°
- Feb 35° 14°
- Mar 44° 21°
- Apr 53° 29°
- May 63° 37°
- Jun 71° 45°
- Jul 82° 51°
- Aug 81° 50°
- Sep 70° 42°
- Oct 56° 31°
- Nov 43° 21°
- Dec 35° 14°
Each month: normal high (large) and low, °F. Fill: the month's normal mean, colder blue to hotter red.
What is the weather like in Lewistown each month?
July is the warmest month, with normal highs of 82°F; January the coldest, with normal lows of 13°F. The most precipitation falls in June (3.35 in), the least in February (0.49 in).
Each month has its own page with the day-by-day normals, the month's records and its recent years:
| Month | High | Low | Mean | Precip. | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|
| January | 34°F | 13°F | 23.7°F | 0.58 | 8 | <1 | 29 | 8 h 50 min |
| February | 35°F | 14°F | 24.6°F | 0.49 | 8 | <1 | 26 | 10 h 20 min |
| March | 44°F | 21°F | 32.9°F | 0.87 | 9 | <1 | 27 | 11 h 50 min |
| April | 53°F | 29°F | 40.9°F | 1.71 | 12 | <1 | 21 | 13 h 30 min |
| May | 63°F | 37°F | 50.0°F | 2.88 | 14 | <1 | 8 | 15 h |
| June | 71°F | 45°F | 58.0°F | 3.35 | 14 | 1 | <1 | 15 h 50 min |
| July | 82°F | 51°F | 66.1°F | 1.76 | 10 | 6 | <1 | 15 h 30 min |
| August | 81°F | 50°F | 65.4°F | 1.69 | 9 | 5 | <1 | 14 h 20 min |
| September | 70°F | 42°F | 55.9°F | 1.39 | 9 | 1 | 3 | 12 h 40 min |
| October | 56°F | 31°F | 43.4°F | 1.27 | 9 | <1 | 17 | 11 h |
| November | 43°F | 21°F | 32.1°F | 0.67 | 7 | <1 | 25 | 9 h 20 min |
| December | 35°F | 14°F | 24.3°F | 0.51 | 7 | <1 | 29 | 8 h 30 min |
| Year (annual) | 56°F | 31°F | 43.1°F | 17.17 | 116 | 13 | 184 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. |
|---|---|---|---|---|
| January | 1°C | −11°C | −4.6°C | 15 mm |
| February | 2°C | −10°C | −4.1°C | 12 mm |
| March | 7°C | −6°C | 0.5°C | 22 mm |
| April | 12°C | −2°C | 4.9°C | 43 mm |
| May | 17°C | 3°C | 10.0°C | 73 mm |
| June | 22°C | 7°C | 14.4°C | 85 mm |
| July | 28°C | 10°C | 18.9°C | 45 mm |
| August | 27°C | 10°C | 18.6°C | 43 mm |
| September | 21°C | 5°C | 13.3°C | 35 mm |
| October | 13°C | −1°C | 6.3°C | 32 mm |
| November | 6°C | −6°C | 0.1°C | 17 mm |
| December | 2°C | −10°C | −4.3°C | 13 mm |
NOAA publishes no 1991-2020 snowfall normal for this station. Lewistown's own co-op station Lewistown (11 mi SSE) does: 112 inches of snow in a normal year (see the other stations below).
Source: NOAA NCEI 1991-2020 monthly normals, station USW00024036; annual normals. Wet days: 0.01 inch or more; 90°F days and freezing nights: NOAA's day counts. Daylight: sunrise to sunset on the 15th, computed from the latitude.
When is the best weather to visit Lewistown?
Normal highs sit between 65°F and 85°F in June, July, August and September. Of those, September has the fewest days with rain (9).
That is a measurement, not a recommendation: it counts the months whose normal afternoon high sits between 65°F and 85°F, where a light layer is enough by day.
Source: NOAA NCEI 1991-2020 monthly normals, station USW00024036.
When is the last frost in Lewistown?
In Lewistown, the last spring frost (32°F) comes after May 23 in half of years and after June 8 in one year in ten; the first autumn frost comes before September 21 in half of years and before September 8 in one year in ten.
Frost-free in half of yearsFrost in 1 to 9 years out of 10Frost most years
- Last spring frost, half of years after
- May 231 year in 10 after June 8; 9 in 10 after May 11
- First autumn frost, half of years before
- September 211 year in 10 before September 8; 9 in 10 before October 3
NOAA puts the median frost-free season at 119 days, and the season without a hard freeze (28°F) at 145 days.
A hard freeze (28°F) comes after May 9 in half of springs and before October 1 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Lewistown in zone 4b in ZIP code 59457, the nearest ZIP area. By the map's own method, the average of each year's coldest night over 1991-2020, Lewistown's NOAA station is in zone 4b: the coldest night of a typical year reaches −23°F (30 complete years).
Frost dates for every NOAA station in Montana · Frost dates by ZIP code
Source: NOAA NCEI 1991-2020 annual normals (frost probabilities), station USW00024036; USDA 2023 Plant Hardiness Zone Map, ZIP listings: PRISM Group, Oregon State University, https://prism.oregonstate.edu, accessed October 8, 2026; the station zone: ACIS daily lows, 1991-2020. A 10% date means one year in ten has a frost after it in spring or before it in autumn.
How hot and how cold does it get in Lewistown?
In a normal year in Lewistown, 13 days a year reach 90°F, 184 nights fall to 32°F or colder and 116 days bring measurable precipitation.
- Days at 90°F or more
- 13a normal year
- Days at 100°F or more
- fewer than 1a normal year
- Nights at 32°F or colder
- 184a normal year
- Days that stay below freezing
- 47high of 32°F or less
- Days with 0.01 inch of precipitation
- 116a normal year
The highest temperature in this station's record (since 1896) is 105°F, on June 21, 1900; the lowest is −46°F, on January 28, 1929.
The wettest calendar year on that record is 1953, with 28.61 in; the snowiest season is 1954–55, with 172.5 inches.
Source: NOAA NCEI 1991-2020 annual normals, station USW00024036; records: ACIS (NOAA Regional Climate Centers), station USW00024036. Records use complete months only; a month missing more than three days is left out.
How humid and windy is Lewistown, and how clear are its skies?
The summer (June-August) dew point averages 44°F. The muggiest month is June, with an average dew point of 46°F; the driest air comes in December (13°F). November is the windiest month (10.3 mph on average), and July has the most clear or nearly clear hours (83%).
| Month | Dew point | Humidity | Afternoon humidity | Wind | Clear or few clouds | Overcast |
|---|---|---|---|---|---|---|
| January | 15°F | 66% | 55% | 10.0 mph | – | – |
| February | 14°F | 65% | 52% | 9.3 mph | – | – |
| March | 23°F | 59% | 41% | 9.7 mph | – | – |
| April | 29°F | 56% | 38% | 9.8 mph | 51% | 21% |
| May | 41°F | 61% | 44% | 9.0 mph | – | – |
| June | 46°F | 56% | 37% | 7.7 mph | 77% | 14% |
| July | 45°F | 47% | 27% | 7.6 mph | 83% | 3% |
| August | 39°F | 47% | 26% | 7.6 mph | 79% | 10% |
| September | 33°F | 54% | 34% | 8.4 mph | – | – |
| October | 23°F | 57% | 41% | 10.1 mph | – | – |
| November | 16°F | 61% | 50% | 10.3 mph | – | – |
| December | 13°F | 65% | 57% | 9.8 mph | – | – |
Source: NOAA NCEI 1991-2020 hourly normals, station USW00024036. Monthly averages of all hours; afternoon humidity at 3 p.m. local standard time; sky as the share of hours NOAA's observations rate clear or few clouds (a dash where NOAA publishes no sky value).
How sunny is Lewistown?
Over a year 77% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around Lewistown, 4.0 kWh per square metre a day. July is the sunniest month (87%) and December the cloudiest (67%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 73% | 1.6 |
| February | 75% | 2.6 |
| March | 72% | 3.7 |
| April | 70% | 4.8 |
| May | 72% | 5.8 |
| June | 77% | 6.6 |
| July | 87% | 7.1 |
| August | 85% | 5.9 |
| September | 79% | 4.3 |
| October | 73% | 2.7 |
| November | 71% | 1.7 |
| December | 67% | 1.2 |
Source: NASA POWER solar climatology, 2001-2020 (CERES SYN1deg). Satellite-based, for the 1-degree cell (about 100 km across) around the station, so it describes the area rather than the airport.
How much heating and cooling does Lewistown need?
A normal year in Lewistown brings 8,177 heating degree days, 52% more than the median U.S. place (5,373), and 229 cooling degree days, 75% fewer than the median (908). Eight months need 300 or more heating degree days, a monthly mean of about 55°F or colder. For gardens and crops, NOAA counts 1,632 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,282 | 0 |
| February | 1,131 | 0 |
| March | 997 | 0 |
| April | 723 | 0 |
| May | 466 | 1 |
| June | 226 | 17 |
| July | 65 | 101 |
| August | 81 | 91 |
| September | 289 | 18 |
| October | 671 | 1 |
| November | 986 | 0 |
| December | 1,262 | 0 |
| Year (annual) | 8,177 | 229 |
Source: NOAA NCEI 1991-2020 monthly normals, station USW00024036. A degree day is one degree of a day's mean temperature below 65°F (heating) or above it (cooling); utilities use them to estimate energy use.
Has Lewistown been warmer than normal lately?
2025 averaged 44.0°F, 0.9°F above the 1991-2020 normal of 43.1°F. 4 of the 5 complete years since 2021 ran warmer than the normal.
| Year | Mean | Against normal | Precip. |
|---|---|---|---|
| 2021 | 44.1°F | +1.0°F | 10.91 |
| 2022 | 42.2°F | −0.9°F | 16.60 |
| 2023 | 44.7°F | +1.6°F | 19.78 |
| 2024 | 44.6°F | +1.5°F | 19.88 |
| 2025 | 44.0°F | +0.9°F | – |
Over 102 complete years from 1898 to 2025, the station's annual mean temperature rose at a fitted 2.5°F per century (+0.14°C per decade). A fitted rate summarizes the whole record; single years swing well above and below it.
Source: observed years: ACIS, station USW00024036; trend: NOAA GHCN-Monthly v4. A year counts only with all twelve months complete.
How does Lewistown's climate compare?
Lewistown is warmer than 49 of the other 140 places with their own NOAA record in Montana, and wetter than 105. Across the 7,247 U.S. stations with normals, its annual mean of 43.1°F is warmer than 12%.
In the Köppen classification computed from these normals, Lewistown is Dfb: continental, no dry season, warm summer. What the classes mean.
Places with the most similar year elsewhere
Measured month by month on the normal high, low and precipitation, among places of 20,000 or more people in other states:
Source: NOAA NCEI 1991-2020 normals for every station PlainClimate covers. Similarity: the root-mean-square difference of the 36 monthly figures, precipitation weighted so an inch counts like 6°F.
Which places near Lewistown share this climate record?
7 places have no NOAA station with 1991-2020 normals of their own, and this station is the nearest full record. A place's own climate can differ from these figures, by several degrees where it sits much higher or lower than the station, nearer the coast, or inside a large city's heat; for the larger places the next nearest records are named with their yearly mean, so the spread around them is visible, and places of 50,000 or more have their own page with NOAA's gridded normals.
- Lewistown Heights, MT484 people · 2 mi N
- Moore, MT201 people · 12 mi SW
- King Ranch Colony, MT23 people · 8 mi W
- Warm Spring Creek, MT18 people · 12 mi NE
- Spring Creek Colony, MT17 people · 11 mi NW
- Brooks, MT0 people · 11 mi N
- Hilger, MT0 people · 15 mi N
Source: Census Bureau 2024 Gazetteer (place centers) and Vintage 2024 population estimates. Distance and direction from the station to each place's center.
What do Lewistown's other NOAA stations record?
3 more NOAA stations keep 1991-2020 normals in or near Lewistown. This page uses Lewistown Municipal Airport; the others differ by site and elevation:
| Station | From this station | Elevation | Year | Jan low | Jul high | Precip. | Snow | Last frost |
|---|---|---|---|---|---|---|---|---|
| Lewistown (11 mi ESE) USC00244979 | 11 mi E | 5,028 ft | 42.5°F | 15°F | 77°F | 20.9 | – | May 19 |
| Lewistown (11 mi SSE) USC00244978 | 10 mi S | 4,965 ft | 42.3°F | 13°F | 80°F | 23.3 | 112 | May 31 |
| Lewistown station USC00244976 | 3 mi NE | 3,911 ft | 46.6°F | 15°F | 87°F | – | – | May 14 |
Source: NOAA NCEI 1991-2020 normals for each station. Last frost: the median last spring date of 32°F.
Questions about Lewistown's climate
What is the coldest month in Lewistown?
January, with a normal high of 34°F and a normal low of 13°F. The warmest is July (82°F by day, 51°F at night).
Does it snow in Lewistown?
Yes. NOAA publishes no 1991-2020 snowfall normal for Lewistown's NOAA station; Lewistown's own co-op station Lewistown (11 mi SSE) records 112 inches of snow in a normal year.
What is the rainiest month in Lewistown?
June, with 3.35 in of precipitation in a normal year; the driest is February with 0.49 in.
What plant hardiness zone is Lewistown in?
The USDA's 2023 map puts Lewistown in zone 4b in ZIP code 59457, the nearest ZIP area. By the same method at Lewistown's NOAA station, the coldest night of a typical year reaches −23°F (30 years, 1991-2020): zone 4b.
How late can frost come in Lewistown?
In half of years the last 32°F night comes after May 23; in one year in ten it comes after June 8. Waiting until June 8 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Lewistown in OctoberThis month day by day, its records and recent years
- Montana climateThe statewide normals and every place in the state
- Moccasin, MT23 miles from this station, 43.5°F a year
- Judith Gap, MT29 miles from this station, 41.6°F a year
- Denton, MT29 miles from this station, 42.8°F a year
- Grass Range, MT31 miles from this station, 45.5°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made