Boise, ID Climate & Monthly Averages
The climate of Boise
Boise has a semi-arid climate, marked by big day-to-night temperature swings and modest rainfall. Average daytime highs range from about 38°F (4°C) in December to around 94°F (34°C) in July, and the city records roughly 77 days of measurable precipitation a year.
Climate quick facts
- Hottest month: July - highs near 94°F (34°C)
- Coldest month: December - highs near 38°F (4°C)
- Record high: 107°F (42°C) · Record low: -10°F (-23°C) (2015–2024)
- Wettest month: December (12 rainy days) · Sunniest: July (14.0 h sun/day)
- Climate type: semi-arid - big day-to-night temperature swings and modest rainfall
- Snow: about 18 days a year
Temperatures through the year
The warmest stretch of the year centers on July. Highs average 94°F (34°C) and overnight lows stay near 65°F (18°C). The coolest month is December, with typical highs of 38°F (4°C) and lows around 25°F (-4°C). Based on 2015–2024 weather data, temperatures have reached as high as 107°F (42°C) and dropped as low as -10°F (-23°C).
Rain, sun and snow
December is usually the wettest month. It brings about 2.2 inches (56 mm) of rain over 12 days, while July is the driest. July brings the most sunshine, averaging 14.0 hours of sun a day. Snow falls on about 18 days in a typical year, mostly from November through April.
Monthly climate table
| Month | High | Low | Rain days | Precipitation | Sunshine | Humidity |
|---|---|---|---|---|---|---|
| January | 39° | 25° | 10 | 2.0 in | 6.4 h/day | 75% |
| February | 45° | 28° | 10 | 1.6 in | 7.5 h/day | 66% |
| March | 54° | 34° | 10 | 1.6 in | 9.2 h/day | 59% |
| April | 62° | 39° | 7 | 1.3 in | 10.9 h/day | 50% |
| May | 71° | 48° | 8 | 1.6 in | 12.2 h/day | 49% |
| June | 83° | 57° | 3 | 0.9 in | 13.4 h/day | 40% |
| July | 94° | 65° | 1 | 0.1 in | 14.0 h/day | 27% |
| August | 91° | 64° | 1 | 0.1 in | 12.9 h/day | 30% |
| September | 80° | 55° | 3 | 0.5 in | 11.1 h/day | 39% |
| October | 65° | 43° | 5 | 1.0 in | 9.2 h/day | 53% |
| November | 49° | 32° | 8 | 1.4 in | 7.1 h/day | 65% |
| December | 38° | 25° | 12 | 2.2 in | 5.6 h/day | 75% |
Boise month by month
Boise weather in January
January brings highs around 39°F (4°C), lows near 25°F (-4°C), about 10 wet days and roughly 4 snowy days.
Boise weather in February
February brings highs around 45°F (7°C), lows near 28°F (-2°C), about 10 wet days and roughly 4 snowy days.
Boise weather in March
March brings highs around 54°F (12°C), lows near 34°F (1°C), about 10 wet days and roughly 2 snowy days.
Boise weather in April
April brings highs around 62°F (16°C), lows near 39°F (4°C), about 7 wet days.
Boise weather in May
May brings highs around 71°F (22°C), lows near 48°F (9°C), about 8 wet days.
Boise weather in June
June brings highs around 83°F (28°C), lows near 57°F (14°C), about 3 wet days.
Boise weather in July
July brings highs around 94°F (34°C), lows near 65°F (18°C), about 1 wet days - typically the hottest month and the driest month and the sunniest month of the year in Boise.
Boise weather in August
August brings highs around 91°F (33°C), lows near 64°F (18°C), about 1 wet days.
Boise weather in September
September brings highs around 80°F (27°C), lows near 55°F (13°C), about 3 wet days.
Boise weather in October
October brings highs around 65°F (18°C), lows near 43°F (6°C), about 5 wet days.
Boise weather in November
November brings highs around 49°F (10°C), lows near 32°F (0°C), about 8 wet days and roughly 2 snowy days.
Boise weather in December
December brings highs around 38°F (4°C), lows near 25°F (-4°C), about 12 wet days and roughly 6 snowy days - typically the coldest month and the wettest month of the year in Boise.
Seasons in Boise
Spring (March through May)
Spring in Boise is crisp but comfortable, with daytime highs averaging 62°F (17°C) and nights around 40°F (5°C); expect showers on roughly 25 days across the season, plus around 3 snowy days.
Summer (June through August)
Summer in Boise runs hot, with daytime highs averaging 89°F (32°C) and nights around 62°F (17°C); precipitation is infrequent.
Fall (September through November)
Fall in Boise is mild, with daytime highs averaging 65°F (18°C) and nights around 43°F (6°C); rain falls on about 16 days over the three months.
Winter (December through February)
Winter in Boise is brisk and cold, with daytime highs averaging 41°F (5°C) and nights around 26°F (-3°C); expect showers on roughly 32 days across the season, plus around 14 snowy days.
Climate questions, answered
What is the average temperature in Boise?
Is Boise hot in summer?
Is Boise cold in winter?
How many rainy days does Boise get in a year?
Best time to visit Boise
The best time to visit Boise is generally September to October and April, when temperatures are at their most comfortable before or after the peak heat. Daytime temperatures in that window typically sit near 72°F (22°C).
Pack for Boise with lightweight, breathable clothing and strong sun protection for the hot months; a heavy insulated coat, hat and gloves for winter; rain gear if you travel around December. Evenings can feel noticeably cooler than afternoons - July nights average 65°F (18°C).
Boise temperature records (2015-2024)
Derived from ERA5 reanalysis data, 2015–2024. Official station records may differ.