Fortine, Montana climate: Normal weather by month, frost dates and records
Fortine's normal year runs from 17°F December nights to 84°F July afternoons, with 15.1 inches of precipitation and 41 inches of snow a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 6.6°C, December lows of −8°C, July highs of 29°C, 382 mm of precipitation a year.
- NOAA stationFortine (1 mi N)
- Station IDUSC00243139
- Location48.78°N 114.90°W
- Elevation3,000 ft (914 m)
- Population (census place)378
On October 22, the normal high in Fortine is 51°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 Fortine.
- Jan 30° 18°
- Feb 35° 19°
- Mar 46° 25°
- Apr 56° 31°
- May 68° 38°
- Jun 73° 45°
- Jul 84° 50°
- Aug 83° 47°
- Sep 72° 40°
- Oct 55° 31°
- Nov 39° 25°
- Dec 29° 17°
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 Fortine each month?
July is the warmest month, with normal highs of 84°F; December the coldest, with normal lows of 17°F. The most precipitation falls in June (2.78 in), the least in February (0.70 in).
| Month | High | Low | Mean | Precip. | Snow | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|---|
| January | 30°F | 18°F | 23.8°F | 0.77 | 9.1 | 9 | <1 | 29 | 8 h 40 min |
| February | 35°F | 19°F | 27.3°F | 0.70 | 5.9 | 7 | <1 | 26 | 10 h 10 min |
| March | 46°F | 25°F | 35.4°F | 0.80 | 5.6 | 7 | <1 | 26 | 11 h 50 min |
| April | 56°F | 31°F | 43.3°F | 1.16 | 2.1 | 7 | <1 | 18 | 13 h 40 min |
| May | 68°F | 38°F | 52.8°F | 1.88 | 0.3 | 9 | <1 | 6 | 15 h 10 min |
| June | 73°F | 45°F | 58.8°F | 2.78 | 0.0 | 10 | 1 | <1 | 16 h 10 min |
| July | 84°F | 50°F | 66.8°F | 1.58 | 0.0 | 6 | 8 | <1 | 15 h 50 min |
| August | 83°F | 47°F | 65.2°F | 0.92 | 0.0 | 4 | 7 | <1 | 14 h 30 min |
| September | 72°F | 40°F | 55.8°F | 1.23 | 0.0 | 7 | 1 | 5 | 12 h 40 min |
| October | 55°F | 31°F | 43.2°F | 0.92 | 0.7 | 6 | <1 | 17 | 10 h 50 min |
| November | 39°F | 25°F | 31.8°F | 1.25 | 7.9 | 10 | <1 | 25 | 9 h 10 min |
| December | 29°F | 17°F | 23.0°F | 1.06 | 9.3 | 10 | <1 | 29 | 8 h 20 min |
| Year (annual) | 56°F | 32°F | 43.9°F | 15.05 | 40.9 | 92 | 16 | 183 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. | Snow |
|---|---|---|---|---|---|
| January | −1°C | −8°C | −4.6°C | 20 mm | 23 cm |
| February | 2°C | −7°C | −2.6°C | 18 mm | 15 cm |
| March | 8°C | −4°C | 1.9°C | 20 mm | 14 cm |
| April | 13°C | −1°C | 6.3°C | 29 mm | 5 cm |
| May | 20°C | 3°C | 11.6°C | 48 mm | 1 cm |
| June | 23°C | 7°C | 14.9°C | 71 mm | 0 cm |
| July | 29°C | 10°C | 19.3°C | 40 mm | 0 cm |
| August | 29°C | 8°C | 18.4°C | 23 mm | 0 cm |
| September | 22°C | 4°C | 13.2°C | 31 mm | 0 cm |
| October | 13°C | 0°C | 6.2°C | 23 mm | 2 cm |
| November | 4°C | −4°C | −0.1°C | 32 mm | 20 cm |
| December | −2°C | −8°C | −5.0°C | 27 mm | 24 cm |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00243139; 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 Fortine?
Normal highs sit between 65°F and 85°F in May, June, July, August and September. Of those, August has the fewest days with rain (4).
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 USC00243139.
When is the last frost in Fortine?
In Fortine, the last spring frost (32°F) comes after May 16 in half of years and after June 3 in one year in ten; the first autumn frost comes before September 18 in half of years and before September 1 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 161 year in 10 after June 3; 9 in 10 after May 3
- First autumn frost, half of years before
- September 181 year in 10 before September 1; 9 in 10 before October 5
NOAA puts the median frost-free season at 121 days, and the season without a hard freeze (28°F) at 154 days.
A hard freeze (28°F) comes after May 1 in half of springs and before October 2 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Fortine in zone 5a in ZIP code 59918, the nearest ZIP area.
Frost dates for every NOAA station in Montana · Frost dates by ZIP code
Source: NOAA NCEI 1991-2020 annual normals (frost probabilities), station USC00243139; USDA 2023 Plant Hardiness Zone Map, ZIP listings: PRISM Group, Oregon State University, https://prism.oregonstate.edu, accessed October 8, 2026. 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 Fortine?
In a normal year in Fortine, 16 days a year reach 90°F, 183 nights fall to 32°F or colder and 92 days bring measurable precipitation.
- Days at 90°F or more
- 16a normal year
- Days at 100°F or more
- fewer than 1a normal year
- Nights at 32°F or colder
- 183a normal year
- Days that stay below freezing
- 53high of 32°F or less
- Days with 0.01 inch of precipitation
- 92a normal year
- Days with 1 inch of snow or more
- 22a normal year
The highest temperature in this station's record (since 1906) is 104°F, on August 4, 1961; the lowest is −42°F, on February 15, 1936.
The wettest calendar year on that record is 1954, with 24.40 in; the snowiest season is 1942–43, with 109.1 inches.
Source: NOAA NCEI 1991-2020 annual normals, station USC00243139; records: ACIS (NOAA Regional Climate Centers), station USC00243139. Records use complete months only; a month missing more than three days is left out.
How sunny is Fortine?
Over a year 70% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around Fortine, 3.6 kWh per square metre a day. July is the sunniest month (85%) and December the cloudiest (50%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 54% | 1.1 |
| February | 62% | 2.0 |
| March | 62% | 3.1 |
| April | 65% | 4.4 |
| May | 68% | 5.5 |
| June | 69% | 6.0 |
| July | 85% | 7.1 |
| August | 83% | 5.8 |
| September | 75% | 4.0 |
| October | 65% | 2.4 |
| November | 53% | 1.2 |
| December | 50% | 0.8 |
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 Fortine need?
A normal year in Fortine brings 7,857 heating degree days, 46% more than the median U.S. place (5,373), and 209 cooling degree days, 77% 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 1,635 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,277 | 0 |
| February | 1,054 | 0 |
| March | 918 | 0 |
| April | 650 | 0 |
| May | 382 | 3 |
| June | 198 | 13 |
| July | 52 | 108 |
| August | 71 | 77 |
| September | 283 | 8 |
| October | 676 | 0 |
| November | 996 | 0 |
| December | 1,300 | 0 |
| Year (annual) | 7,857 | 209 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00243139. 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.
How does Fortine's climate compare?
Fortine is warmer than 71 of the other 140 places with their own NOAA record in Montana, and wetter than 73. Across the 7,247 U.S. stations with normals, its annual mean of 43.9°F is warmer than 15%.
In the Köppen classification computed from these normals, Fortine 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 Fortine 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.
- Trego, MT856 people · 9 mi S
- Stryker, MT0 people · 9 mi SE
Source: Census Bureau 2024 Gazetteer (place centers) and Vintage 2024 population estimates. Distance and direction from the station to each place's center.
Questions about Fortine's climate
What is the coldest month in Fortine?
December, with a normal high of 29°F and a normal low of 17°F. The warmest is July (84°F by day, 50°F at night).
Does it snow in Fortine?
Yes: 41 inches in a normal year, falling on 27 days with 0.1 inch or more, the most in December (9.3 inches).
What is the rainiest month in Fortine?
June, with 2.78 in of precipitation in a normal year; the driest is February with 0.70 in.
What plant hardiness zone is Fortine in?
The USDA's 2023 map puts Fortine in zone 5a in ZIP code 59918, the nearest ZIP area.
How late can frost come in Fortine?
In half of years the last 32°F night comes after May 16; in one year in ten it comes after June 3. Waiting until June 3 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Montana climateThe statewide normals and every place in the state
- Eureka, MT11 miles from this station, 47.0°F a year
- Olney, MT22 miles from this station, 39.6°F a year
- Polebridge, MT28 miles from this station, 39.6°F a year
- Libby Dam (Base), MT32 miles from this station, 46.4°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made