Big Sky, Montana climate: Normal weather by month, frost dates and records
Big Sky's normal year runs from 9°F December nights to 78°F July afternoons, with 23.3 inches of precipitation a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 3.2°C, December lows of −13°C, July highs of 25°C, 592 mm of precipitation a year.
- NOAA stationBig Sky (2 mi WNW)
- Station IDUSC00240775
- Location45.28°N 111.33°W
- Elevation6,590 ft (2,009 m)
- Population (census place)2,388
On October 23, the normal high in Big Sky is 49°F and the normal low 22°F, and the chance of measurable rain or snow is 32%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Big Sky.
- Jan 30° 9°
- Feb 34° 9°
- Mar 42° 17°
- Apr 48° 23°
- May 58° 30°
- Jun 67° 36°
- Jul 78° 41°
- Aug 77° 39°
- Sep 68° 33°
- Oct 53° 25°
- Nov 37° 16°
- Dec 28° 9°
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 Big Sky each month?
July is the warmest month, with normal highs of 78°F; December the coldest, with normal lows of 9°F. The most precipitation falls in June (3.22 in), the least in July (1.25 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 | 30°F | 9°F | 19.2°F | 1.83 | 13 | <1 | 31 | 9 h 10 min |
| February | 34°F | 9°F | 21.5°F | 1.51 | 12 | <1 | 28 | 10 h 20 min |
| March | 42°F | 17°F | 29.3°F | 1.88 | 12 | <1 | 31 | 11 h 50 min |
| April | 48°F | 23°F | 35.2°F | 2.42 | 12 | <1 | 29 | 13 h 30 min |
| May | 58°F | 30°F | 44.1°F | 2.83 | 13 | <1 | 22 | 14 h 50 min |
| June | 67°F | 36°F | 51.4°F | 3.22 | 14 | <1 | 10 | 15 h 40 min |
| July | 78°F | 41°F | 59.5°F | 1.25 | 10 | 1 | 2 | 15 h 20 min |
| August | 77°F | 39°F | 58.0°F | 1.56 | 11 | <1 | 3 | 14 h 10 min |
| September | 68°F | 33°F | 50.8°F | 1.70 | 10 | <1 | 15 | 12 h 40 min |
| October | 53°F | 25°F | 38.8°F | 1.77 | 10 | <1 | 27 | 11 h |
| November | 37°F | 16°F | 26.2°F | 1.60 | 11 | <1 | 29 | 9 h 30 min |
| December | 28°F | 9°F | 18.0°F | 1.74 | 14 | <1 | 31 | 8 h 50 min |
| Year (annual) | 52°F | 24°F | 37.7°F | 23.31 | 140 | 1 | 257 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. |
|---|---|---|---|---|
| January | −1°C | −13°C | −7.1°C | 46 mm |
| February | 1°C | −13°C | −5.8°C | 38 mm |
| March | 6°C | −9°C | −1.5°C | 48 mm |
| April | 9°C | −5°C | 1.8°C | 61 mm |
| May | 15°C | −1°C | 6.7°C | 72 mm |
| June | 19°C | 2°C | 10.8°C | 82 mm |
| July | 25°C | 5°C | 15.3°C | 32 mm |
| August | 25°C | 4°C | 14.4°C | 40 mm |
| September | 20°C | 1°C | 10.4°C | 43 mm |
| October | 12°C | −4°C | 3.8°C | 45 mm |
| November | 3°C | −9°C | −3.2°C | 41 mm |
| December | −2°C | −13°C | −7.8°C | 44 mm |
NOAA publishes no 1991-2020 snowfall normal for this station. The nearest record that keeps one, Ennis (19 miles away), gets 45 inches of snow in a normal year; elevation and distance can change that.
Source: NOAA NCEI 1991-2020 monthly normals, station USC00240775; 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 Big Sky?
Normal highs sit between 65°F and 85°F in June, July, August and September. Of those, September has the fewest days with rain (10).
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 USC00240775.
How hot and how cold does it get in Big Sky?
In a normal year in Big Sky, 1 day a year reaches 90°F, 257 nights fall to 32°F or colder and 140 days bring measurable precipitation.
- Days at 90°F or more
- 1a normal year
- Days at 100°F or more
- fewer than 1a normal year
- Nights at 32°F or colder
- 257a normal year
- Days that stay below freezing
- 61high of 32°F or less
- Days with 0.01 inch of precipitation
- 140a normal year
The highest temperature in this station's record (since 1967) is 95°F, on July 13, 2002; the lowest is −42°F, on February 3, 1989.
The wettest calendar year on that record is 2014, with 26.68 in; the snowiest season is 2007–08, with 244.9 inches.
Source: NOAA NCEI 1991-2020 annual normals, station USC00240775; records: ACIS (NOAA Regional Climate Centers), station USC00240775. Records use complete months only; a month missing more than three days is left out.
How sunny is Big Sky?
Over a year 74% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around Big Sky, 4.1 kWh per square metre a day. July is the sunniest month (84%) and December the cloudiest (63%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 69% | 1.7 |
| February | 73% | 2.8 |
| March | 70% | 3.8 |
| April | 66% | 4.8 |
| May | 67% | 5.6 |
| June | 75% | 6.6 |
| July | 84% | 7.2 |
| August | 83% | 6.1 |
| September | 79% | 4.6 |
| October | 69% | 2.9 |
| November | 66% | 1.8 |
| December | 63% | 1.3 |
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 Big Sky need?
A normal year in Big Sky brings 9,955 heating degree days, 85% more than the median U.S. place (5,373), and 11 cooling degree days, 99% fewer than the median (908). Ten months need 300 or more heating degree days, a monthly mean of about 55°F or colder. For gardens and crops, NOAA counts 778 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,421 | 0 |
| February | 1,218 | 0 |
| March | 1,107 | 0 |
| April | 893 | 0 |
| May | 650 | 0 |
| June | 408 | 0 |
| July | 180 | 7 |
| August | 220 | 3 |
| September | 428 | 0 |
| October | 812 | 0 |
| November | 1,163 | 0 |
| December | 1,457 | 0 |
| Year (annual) | 9,955 | 11 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00240775. 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 Big Sky's climate compare?
Big Sky is warmer than 6 of the other 140 places with their own NOAA record in Montana, and wetter than 123. Across the 7,247 U.S. stations with normals, its annual mean of 37.7°F is warmer than 3%.
In the Köppen classification computed from these normals, Big Sky 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.
Questions about Big Sky's climate
What is the coldest month in Big Sky?
December, with a normal high of 28°F and a normal low of 9°F. The warmest is July (78°F by day, 41°F at night).
Does it snow in Big Sky?
Yes. NOAA publishes no 1991-2020 snowfall normal for Big Sky's NOAA station; the nearest record that keeps one, Ennis (19 miles away), records 45 inches of snow in a normal year.
What is the rainiest month in Big Sky?
June, with 3.22 in of precipitation in a normal year; the driest is July with 1.25 in.
What plant hardiness zone is Big Sky in?
The USDA's 2023 map puts Big Sky in zone 4b in ZIP code 59716.
Nearby and next
- Big Sky in OctoberThis month day by day, its records and recent years
- Montana climateThe statewide normals and every place in the state
- Ennis, MT19 miles from this station, 42.7°F a year
- Norris, MT21 miles from this station, 49.2°F a year
- Hebgen Dam, MT29 miles from this station, 37.0°F a year
- Virginia City, MT30 miles from this station, 43.9°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made