Photo: Greg Gjerdingen · CC BY 2.0Big Sky’s winters are colder than most of the U.S.; July afternoons average 78°
A typical July afternoon reaches 78°, a January night drops to 8°.
A year in Big Sky at a glance
Each month’s typical high and low, and what it brings.
What stands out about Big Sky’s climate
Compared with towns across the U.S., with Big Sky’s place in Montana beside it.
What a year in Big Sky feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
A freeze is possible in every month
About 257 nights a year fall to 32° or below, and 29 to 0° or below. Frost dates and degree days from Big Sky 2wnw, MT, 1.5 miles away.
The 2023 USDA map puts Big Sky’s center in zone 4b: the coldest night of a typical winter, averaged over 1991–2020, reaches about −24°. Plant labels use the zone; frost dates tell you when to plant.
Freezing nights by month
Average nights at or below 32°
90° days by month
Average days at 90° or more
About 21 inches of rain a year
June is the wettest month and February the driest.
Rain + melted snow by month
Inches of water
Heating and cooling a home in Big Sky
Nearly all of the work is heating: a normal year has almost no cooling days. Months averaging under 55° run from September through June.
Degree days add up how far each day’s average falls below (heating) or rises above (cooling) 65° over a year. NOAA normals at Big Sky 2wnw, MT.
Living with Big Sky’s climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
Zone 4b, and frost can come in any month. The longest frost-free stretch in half of years is about 50 days.
Months with highs of 62–84° and lows of 40° or more: July and August. 174 miles of trails are waiting.
Parks & trails →Of the yearly building losses FEMA expects in Big Sky from natural hazards, avalanches are the largest share (70%); heat waves, cold waves, winter storms and ice storms together are 5%. Normals are averages; the hazards page covers the extremes.
Natural hazards →Big Sky and similar climates
TownRatings has no climate map of the towns around Big Sky yet.
Temperatures and precipitation come from NOAA’s 5 km grid; snow and day counts from the stations named on this page.
Warmer than it used to be
The last 30 years in Big Sky averaged 1.2° warmer than the 1900s. The biggest change is in January (+3.4°).
A smaller shift than in 62% of U.S. towns.
Change by month
The two periods overlap (1991–2000 is in both), which makes the gap a little smaller than it would be between separate periods.
How Big Sky compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Big Sky’s place among Montana’s.
Big Sky weather by month
Highs, lows and precipitation from NOAA’s grid at Big Sky’s center. 1991–2020 normals.
| Month | High | Low | Rain + melt | 30-yr range |
|---|---|---|---|---|
| January | 30° | 8° | 1.4" | 13° – 25° |
| February | 33° | 9° | 1.2" | 15° – 28° |
| March | 42° | 16° | 1.4" | 23° – 34° |
| April | 48° | 23° | 2.0" | 30° – 41° |
| May | 58° | 31° | 2.7" | 38° – 49° |
| June | 67° | 37° | 2.9" | 45° – 59° |
| July | 78° | 42° | 1.5" | 49° – 66° |
| August | 77° | 40° | 1.5" | 53° – 62° |
| September | 67° | 34° | 1.6" | 46° – 54° |
| October | 52° | 25° | 1.9" | 30° – 45° |
| November | 37° | 15° | 1.5" | 17° – 34° |
| December | 29° | 8° | 1.5" | 12° – 22° |
| Year | 51° | 24° | 21.2" |
How much a month can swing
A normal is an average. November swings the most: from 1991 to 2020 its average ranged from 17° to 34°. September is the most reliable, staying within 8°.
Where Big Sky’s numbers come from
Normals are 30-year averages, not a forecast. How TownRatings reads climate data →
- Temperatures and precipitation: NOAA’s gridded 1991–2020 normals for the 5 km cell at Big Sky’s center.
- Frost dates, heating and cooling: Big Sky 2wnw, MT, 1.5 miles away.
- Growing zone: USDA Plant Hardiness Zone Map, 2023. USDA Agricultural Research Service and PRISM Group, Oregon State University, prism.oregonstate.edu/phzm, accessed 8 Oct 2026.
- Then and now: NOAA’s gridded normals for 1901–2000 at the same cell.
- Storms and extremes: FEMA National Risk Index (expected annual losses to buildings).
Common questions about Big Sky’s climate
What is the weather like in Big Sky?
A typical July afternoon reaches 78°, a January night drops to 8°. Colder January nights than 96% of U.S. towns; cooler July afternoons than 96% of U.S. towns.
How cold does it get in Big Sky in winter?
December nights average 8°. About 257 nights a year reach 32° or below and 29 reach 0° or below. In the coldest December of the last 30 years the month averaged 12°.
How hot does it get in Big Sky?
July, with a typical high of 78° and a low of 42°. About 1 days a year reach 90° (Big Sky 2wnw, MT).
When is the first and last frost in Big Sky?
There is no reliable frost-free season: at Big Sky 2wnw, MT, every month has nights at 32° or below, about 257 a year. In half of years the longest stretch without a freeze is about 50 days.
What growing zone is Big Sky in?
Zone 4b on the 2023 USDA Plant Hardiness Zone Map: the coldest night of a typical winter reaches about −24°.
What is the best time of year to visit Big Sky?
By one simple rule (highs of 62–84° and lows of 40° or more), July and August. The rule is ours, not NOAA’s; the month table has the numbers to judge by.
Is Big Sky getting warmer?
Yes: 1991–2020 averaged 1.2° warmer than 1901–2000 on NOAA’s grid. A smaller shift than 62% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in Big Sky.
Source: NOAA NCEI U.S. Climate Normals, 1991–2020 and 1901–2000; USDA/PRISM 2023 hardiness zones; FEMA National Risk Index. Today’s forecast: National Weather Service.