Big Sky, MT weather in August
August in Big Sky: mild, with frequent rain. Highs 77°F, lows 39°F, rain on about 11 days. This is the peak of the warm season in Big Sky. A great month for outdoor plans.
- Normal high
- 77°F
- Normal low
- 39°F
- Wet days
- 11
- 1.6 in total
- Daylight
- 14.1 h
How August changes from start to finish
| August 1 | August 31 | |
|---|---|---|
| Normal high | 80°F | 73°F |
| Normal low | 42°F | 36°F |
| Chance of a wet day | 35% | 34% |
| Sunrise / sunset | 6:10 am / 8:53 pm | 6:46 am / 8:05 pm |
| Daylight | 14.7 h | 13.3 h |
Chance of a wet day: average for the first and last 7 days of the month. Times are local clock time (Mountain Time).
What kind of days to expect
- Comfortable dayshigh 65-80°F (temperature only: no humidity station nearby)18 of 31
- Hot dayshigh 90°F or more0 of 31
- Wet daysat least 0.01 in of rain or melted snow11 of 31
- Notable rainat least 0.10 in6 of 31
- Freezing nightslow 32°F or below3 of 31
Average days per August, counted from daily records for each year 1991-2020.
Rain in August
Normal precipitation is 1.6 in; a dry August brings about 1.1 in and a wet one about 2.1 in (25th and 75th percentiles). Days with half an inch or more are rare.
How August varies from year to year
- Warmest August, 1991-20202001: average high 83°F
- Coolest August2014: average high 72°F
- Wettest August2005: 3.4 in
- Driest August2001: 0.09 in
- Highest reading92°F (August 16, 2003)
- Lowest reading20°F (August 26, 1992)
From the station's daily records with NOAA quality flags removed; most recent date shown when a reading repeats.
August compared with July and September
| July | August | September | |
|---|---|---|---|
| Normal high | 78°F | 77°F | 68°F |
| Normal low | 41°F | 39°F | 33°F |
| Wet days | 10 | 11 | 10 |
| Comfortable days | 17 | 18 | 20 |
| Daylight | 15.2 h | 14.1 h | 12.5 h |
Highs change by -1°F from July and -9°F into September.
Nearby alternatives in August
- Warmer: Billings, MT143 mi · high 85°F · 6 wet days
- Drier: West Yellowstone, MT45 mi · high 78°F · 6 wet days
How Big Sky ranks in August
- Normal high347th warmest of 378 cities; 6th of 6 in Montana
- Wet days312th driest of 378
What to pack for Big Sky in August
- A warm jacket – lows near 39°F, highs near 77°F
- Layers – afternoons near 77°F but nights near 39°F
- A rain jacket or umbrella – rain on about 11 days
- Sunglasses and sunscreen – about 14.1 hours of daylight and highs near 77°F
Heating and cooling
August has 220 heating degree days and 3 cooling degree days (base 65°F), 2% of the year's total heating and cooling demand.
Questions
How hot is Big Sky in August?
The normal high is 77°F and the normal low is 39°F. From 1991 to 2020 the hottest August reading was 92°F (August 16, 2003).
Does it rain a lot in Big Sky in August?
About 11 days in August have at least 0.01 in of precipitation, and the normal total is 1.6 in. The wettest August in 1991-2020 was in 2005 (3.4 in); the driest was in 2001 (0.09 in).
Is August a good time to visit Big Sky?
August ranks 3rd of 12 months on our comfort score for Big Sky (76 out of 100). It has about 18 comfortable days (judged by temperature only). The best months are June, July and September.
Where the numbers come from
- Temperature and rain: Big Sky 2WNW (USC00240775), 2.1 mi ESE of the city center, 6,590 ft (630 ft lower than the city). NOAA normals and daily records, 1991-2020.
- Not available for this location: snowfall, snow depth, frost dates, humidity and wind by hour, cloud cover and daily humidity and wind (no station close enough or similar enough in elevation).