Great Falls, Montana climate: Normal weather by month, frost dates and records
Great Falls's normal year runs from 15°F January nights to 84°F July afternoons, with 14.8 inches of precipitation and 66 inches of snow a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 7.0°C, January lows of −9°C, July highs of 29°C, 375 mm of precipitation a year.
- NOAA stationGreat Falls Airport
- Station IDUSW00024143
- Location47.47°N 111.38°W
- Elevation3,664 ft (1,117 m)
- From the center4 miles
- Population60,013
On October 22, the normal high in Great Falls is 54°F and the normal low 30°F, and the chance of measurable rain or snow is 23%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Great Falls.
- Jan 35° 15°
- Feb 37° 15°
- Mar 46° 22°
- Apr 55° 30°
- May 65° 38°
- Jun 73° 46°
- Jul 84° 51°
- Aug 83° 50°
- Sep 72° 43°
- Oct 57° 33°
- Nov 44° 24°
- Dec 36° 16°
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 Great Falls each month?
July is the warmest month, with normal highs of 84°F; January the coldest, with normal lows of 15°F. The most precipitation falls in June (2.72 in), the least in December (0.53 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. | Snow | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|---|
| January | 35°F | 15°F | 25.2°F | 0.55 | 9.2 | 7 | <1 | 27 | 8 h 50 min |
| February | 37°F | 15°F | 26.2°F | 0.59 | 10.1 | 8 | <1 | 25 | 10 h 10 min |
| March | 46°F | 22°F | 34.1°F | 0.68 | 10.1 | 8 | <1 | 25 | 11 h 50 min |
| April | 55°F | 30°F | 42.4°F | 1.73 | 9.4 | 10 | <1 | 18 | 13 h 30 min |
| May | 65°F | 38°F | 51.5°F | 2.43 | 1.9 | 11 | <1 | 6 | 15 h |
| June | 73°F | 46°F | 59.4°F | 2.72 | 0.3 | 12 | 1 | <1 | 16 h |
| July | 84°F | 51°F | 67.9°F | 1.23 | 0.0 | 7 | 10 | <1 | 15 h 40 min |
| August | 83°F | 50°F | 66.7°F | 1.22 | 0.3 | 7 | 9 | <1 | 14 h 20 min |
| September | 72°F | 43°F | 57.2°F | 1.33 | 0.8 | 7 | 2 | 2 | 12 h 40 min |
| October | 57°F | 33°F | 44.8°F | 1.07 | 5.2 | 7 | <1 | 15 | 11 h |
| November | 44°F | 24°F | 33.6°F | 0.68 | 9.2 | 7 | <1 | 23 | 9 h 20 min |
| December | 36°F | 16°F | 26.0°F | 0.53 | 9.6 | 7 | <1 | 27 | 8 h 30 min |
| Year (annual) | 57°F | 32°F | 44.6°F | 14.76 | 66.1 | 98 | 22 | 168 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. | Snow |
|---|---|---|---|---|---|
| January | 2°C | −9°C | −3.8°C | 14 mm | 23 cm |
| February | 3°C | −9°C | −3.2°C | 15 mm | 26 cm |
| March | 8°C | −5°C | 1.2°C | 17 mm | 26 cm |
| April | 13°C | −1°C | 5.8°C | 44 mm | 24 cm |
| May | 18°C | 4°C | 10.8°C | 62 mm | 5 cm |
| June | 23°C | 8°C | 15.2°C | 69 mm | 1 cm |
| July | 29°C | 11°C | 19.9°C | 31 mm | 0 cm |
| August | 28°C | 10°C | 19.3°C | 31 mm | 1 cm |
| September | 22°C | 6°C | 14.0°C | 34 mm | 2 cm |
| October | 14°C | 0°C | 7.1°C | 27 mm | 13 cm |
| November | 7°C | −5°C | 0.9°C | 17 mm | 23 cm |
| December | 2°C | −9°C | −3.3°C | 13 mm | 24 cm |
Source: NOAA NCEI 1991-2020 monthly normals, station USW00024143; 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 Great Falls?
Normal highs sit between 65°F and 85°F in June, July, August and September. Of those, August has the fewest days with rain (7).
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 USW00024143.
When is the last frost in Great Falls?
In Great Falls, the last spring frost (32°F) comes after May 19 in half of years and after June 2 in one year in ten; the first autumn frost comes before September 24 in half of years and before September 9 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 191 year in 10 after June 2; 9 in 10 after May 7
- First autumn frost, half of years before
- September 241 year in 10 before September 9; 9 in 10 before October 5
NOAA puts the median frost-free season at 126 days, and the season without a hard freeze (28°F) at 149 days.
A hard freeze (28°F) comes after May 5 in half of springs and before October 3 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Great Falls in zone 4b in ZIP code 59401. By the map's own method, the average of each year's coldest night over 1991-2020, Great Falls's NOAA station is in zone 4b: the coldest night of a typical year reaches −25°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 USW00024143; 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 Great Falls?
In a normal year in Great Falls, 22 days a year reach 90°F (1 of them 100°F or more), 168 nights fall to 32°F or colder and 98 days bring measurable precipitation.
- Days at 90°F or more
- 22a normal year
- Days at 100°F or more
- 1a normal year
- Nights at 32°F or colder
- 168a normal year
- Days that stay below freezing
- 42high of 32°F or less
- Days with 0.01 inch of precipitation
- 98a normal year
- Days with 1 inch of snow or more
- 20a normal year
The highest temperature in Great Falls's official record (kept by the National Weather Service since 1891) is 107°F, on July 25, 1933; the lowest is −49°F, on February 15, 1936.
The wettest calendar year on that record is 1975, with 25.24 in; the snowiest season is 1988–89, with 117.5 inches.
Source: NOAA NCEI 1991-2020 annual normals, station USW00024143; records: ACIS (NOAA Regional Climate Centers), NWS threaded record GTFthr. Records use complete months only; a month missing more than three days is left out.
How humid and windy is Great Falls, and how clear are its skies?
The summer (June-August) dew point averages 43°F. The muggiest month is June, with an average dew point of 45°F; the driest air comes in December (13°F). November is the windiest month (13.7 mph on average), and July has the most clear or nearly clear hours (78%).
| Month | Dew point | Humidity | Afternoon humidity | Wind | Clear or few clouds | Overcast |
|---|---|---|---|---|---|---|
| January | 15°F | 60% | 47% | 13.1 mph | 61% | 23% |
| February | 15°F | 61% | 45% | 11.5 mph | 55% | 27% |
| March | 23°F | 56% | 38% | 11.6 mph | 54% | 27% |
| April | 30°F | 52% | 34% | 11.2 mph | 54% | 23% |
| May | 41°F | 58% | 39% | 9.8 mph | 54% | 22% |
| June | 45°F | 51% | 31% | 9.1 mph | 69% | 10% |
| July | 44°F | 42% | 23% | 8.8 mph | 78% | 6% |
| August | 39°F | 42% | 23% | 9.2 mph | 75% | 9% |
| September | 34°F | 51% | 33% | 10.7 mph | 71% | 16% |
| October | 24°F | 56% | 41% | 12.7 mph | 63% | 21% |
| November | 17°F | 59% | 49% | 13.7 mph | 64% | 22% |
| December | 13°F | 61% | 53% | 13.4 mph | 61% | 24% |
Source: NOAA NCEI 1991-2020 hourly normals, station USW00024143. 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 Great Falls?
Over a year 76% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around Great Falls, 4.0 kWh per square metre a day. July is the sunniest month (87%) and December the cloudiest (66%). Among the 459 U.S. places of 50,000 or more, that ranks tied 276th (with 27 others) in sunshine.
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 71% | 1.5 |
| February | 73% | 2.5 |
| March | 71% | 3.6 |
| April | 69% | 4.8 |
| May | 71% | 5.8 |
| June | 76% | 6.6 |
| July | 87% | 7.2 |
| August | 85% | 5.9 |
| September | 78% | 4.3 |
| October | 72% | 2.7 |
| November | 68% | 1.6 |
| December | 66% | 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 Great Falls need?
A normal year in Great Falls brings 7,722 heating degree days, 44% more than the median U.S. place (5,373), and 310 cooling degree days, 66% 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 1,848 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,235 | 0 |
| February | 1,085 | 0 |
| March | 958 | 0 |
| April | 678 | 0 |
| May | 422 | 3 |
| June | 193 | 24 |
| July | 48 | 136 |
| August | 66 | 120 |
| September | 258 | 25 |
| October | 628 | 2 |
| November | 941 | 0 |
| December | 1,210 | 0 |
| Year (annual) | 7,722 | 310 |
Source: NOAA NCEI 1991-2020 monthly normals, station USW00024143. 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 Great Falls been warmer than normal lately?
2025 averaged 46.1°F, 1.5°F above the 1991-2020 normal of 44.6°F. 4 of the 5 complete years since 2021 ran warmer than the normal.
| Year | Mean | Against normal | Precip. | Snow |
|---|---|---|---|---|
| 2021 | 45.5°F | +0.9°F | 11.19 | 45.9 |
| 2022 | 44.3°F | −0.4°F | 15.02 | 83.6 |
| 2023 | 46.8°F | +2.2°F | 17.10 | 68.2 |
| 2024 | 46.2°F | +1.6°F | 13.83 | 49.6 |
| 2025 | 46.1°F | +1.5°F | 12.17 | 48.0 |
Over 129 complete years from 1893 to 2025, the station's annual mean temperature rose at a fitted 0.8°F per century (+0.04°C per decade). A fitted rate summarizes the whole record; single years swing well above and below it.
Source: observed years: ACIS, station USW00024143; trend: NOAA GHCN-Monthly v4. A year counts only with all twelve months complete.
How does Great Falls's climate compare?
Great Falls is warmer than 83 of the other 140 places with their own NOAA record in Montana, and wetter than 63. Across the 7,247 U.S. stations with normals, its annual mean of 44.6°F is warmer than 18%.
In the Köppen classification computed from these normals, Great Falls is BSk: cold semi-arid steppe. 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 Great Falls share this climate record?
2 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.
- Sun Prairie, MT1,514 people · 7 mi NW
- Ulm, MT868 people · 8 mi SW
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 Great Falls's other NOAA stations record?
2 more NOAA stations keep 1991-2020 normals in or near Great Falls. This page uses Great Falls Airport; the others differ by site and elevation, and the linked ones have pages of their own:
| Station | From the center | Elevation | Year | Jan low | Jul high | Precip. | Snow | Last frost |
|---|---|---|---|---|---|---|---|---|
| Great Falls 16ST USC00243749 | 1 mi SE | 3,505 ft | 47.0°F | 18°F | 86°F | 15.4 | – | May 6 |
| Great Falls Weather Office USC00243753 | 5 mi SW | 3,705 ft | 45.2°F | 16°F | 83°F | 14.6 | 69 | May 12 |
Source: NOAA NCEI 1991-2020 normals for each station. Last frost: the median last spring date of 32°F.
Questions about Great Falls's climate
What is the coldest month in Great Falls?
January, with a normal high of 35°F and a normal low of 15°F. The warmest is July (84°F by day, 51°F at night).
Does it snow in Great Falls?
Yes: 66 inches in a normal year, falling on 45 days with 0.1 inch or more, the most in February (10.1 inches).
What is the rainiest month in Great Falls?
June, with 2.72 in of precipitation in a normal year; the driest is December with 0.53 in.
What plant hardiness zone is Great Falls in?
The USDA's 2023 map puts Great Falls in zone 4b in ZIP code 59401. By the same method at Great Falls's NOAA station, the coldest night of a typical year reaches −25°F (30 years, 1991-2020): zone 4b.
How late can frost come in Great Falls?
In half of years the last 32°F night comes after May 19; in one year in ten it comes after June 2. Waiting until June 2 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Great Falls in OctoberThis month day by day, its records and recent years
- Montana climateThe statewide normals and every place in the state
- Great Falls 16ST, MT5 miles from this station, 47.0°F a year
- Sun River (4 mi S), MT17 miles from this station, 43.6°F a year
- Carter (14 mi W), MT23 miles from this station, 43.9°F a year
- Cascade, MT24 miles from this station, 47.0°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made