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Big Sky, MT Weather
Big Sky, Montana sits at 45.2564, -111.3320. Its warmest month is July, when the day usually reaches 68F, and its coldest is February, when the night usually falls to 12F. April is the wettest, with rain on about 16 days. The hottest day in the station record is 86F on July 12, 2002, and the coldest night -33F on February 16, 2006. This page carries live conditions, an hour by hour timeline, a ten day outlook, radar, monthly averages and searchable daily history back to 1940.
About Big Sky weather
Big Sky sits at 45.2564, -111.3320 and covers about 120.005 square miles. The forecast above is live: current conditions lead with the HRRR model, corrected against the nearest reporting station and against radar overhead, because a model can lag a storm and the radar cannot.
The tabs at the top of this page carry the hour by hour timeline, the ten day outlook and live radar. Where the models disagree about a day, the rock says so on the day rather than quietly picking a winner.
The rock grades itself against what actually happened and publishes the result whether it flatters it or not. Those standings live in the Receipts.
Where these numbers come from
Current conditions and forecast: NOAA forecast grids (the National Weather Service digital forecast, the National Blend of Models, HRRR and GFS) decoded on our own server, corrected against the nearest reporting station and our own radar. Open-Meteo is consulted only as a fallback when our server is silent.
Radar: NOAA MRMS merged reflectivity, rendered into tiles by myweatherrock.
Monthly averages and records: computed by myweatherrock from NOAA GHCN-Daily station records at the nearest qualifying station, named on this page with its distance. Measurements, not estimates.
Daily history search: the town's own NOAA GHCN-Daily station file, held on our server, measurements by day. Months the station missed fall back to the Open-Meteo historical archive (reanalysis), and the page says so when it does.
What the weather is usually like in Big Sky
Big Sky is warmest in July, when the day usually reaches 68F, and coldest in February, when the night usually falls to 12F. April is the wettest month, with rain on about 16 days of it.
Usual high and low, by month
Days with rain, by month
The same year as numbers
Month
Usual high
Usual low
Rain days
January
29F
13F
15
February
30F
12F
13
March
37F
18F
14
April
43F
22F
16
May
51F
31F
15
June
58F
38F
13
July
68F
46F
8
August
67F
45F
8
September
57F
38F
9
October
44F
27F
12
November
33F
18F
13
December
27F
12F
14
Thirty-year normals, 1991 to 2020, computed from the daily record, measured at the Lone Mountain station 4.9 miles away. A rain day means at least a hundredth of an inch fell, the same measurable-precipitation mark the Weather Service uses. Source: computed from the station record, NOAA GHCN daily.
Big Sky weather history, back to 1940
Pick any month back to 1940 and see what the archive holds for Big Sky: the reanalysis record of what happened, day by day.
Reading this month last year to start you off.
Big Sky weather records
In 36,316 days of observations Big Sky has been as hot as 86F and as cold as -33F. Not averages: the actual days.
Hottest day
86F
July 12, 2002
Coldest night
-34F
February 16, 2006
Wettest day
2.00 in
October 22, 2022
Biggest snow
14.0 in
January 13, 1928
NOAA GHCN daily station records, observed 1991 to 2025: temperature at the Lone Mountain station, 4.9 miles away; snowfall at the Ennis station, 19.4 miles away. Station measurements, not estimates. Record dates reflect the station's own observation schedule, and the official state record may live at a different station.
Common questions about Big Sky weather
Common questions
What is the weather usually like in Big Sky, MT?
Big Sky is warmest in July, when the day usually reaches 68F, and coldest in February, when the night usually falls to 12F. Rain falls on roughly 150 days a year, most often in April. Averages are thirty-year normals, 1991 to 2020, computed from the nearest NOAA station's own daily record.
How much does it rain in Big Sky, MT?
About 150 days a year see at least a hundredth of an inch, which is the Weather Service's measurable-precipitation mark. April is the wettest month with rain on about 16 of its days, and July the driest with about 8.
What is the hottest it has ever been in Big Sky, MT?
The hottest day measured for Big Sky reached 86F on July 12, 2002, and the coldest night -33F on February 16, 2006. Both are real NOAA station measurements from the GHCN daily archive, observed 1991 to 2025, at the Lone Mountain station. Not estimates, though the official state record may live at a different station.
Can I look up past weather for Big Sky, MT?
Yes, and for free. The History tab on this page takes any month back to 1940 and shows every day of it: the high, the low, what fell, and that month's hottest and coldest day. No account and no payment.
Is the Big Sky forecast on this page free, and does it track me?
It is free, carries no advertising, and needs no account. Nothing about a visitor leaves the device except the coordinates needed to fetch a forecast, and those are not stored against anyone.