Air Quality Alert
* WHAT...Air Quality Advisory because of degraded air quality.
Air Quality Index is forecast to be Unhealthy.
* WHERE...Ada, Adams, Boise, Canyon, Elmore, Gem, Owyhee, Payette,
Valley, and Washington Counties.
* WHEN...UNTIL 2 PM MDT FRIDAY.
* IMPACTS...Everyone may begin to …
Heat Advisory
* WHAT...Afternoon temperatures in the triple digits for lower
elevations and the high desert, mid to upper 90s for higher
terrain. Some mild relief overnight with minimum temperatures in
the mid to upper 60s in lower elevations and 50s in the higher
terrain.
* WHERE...Portions …
Heat Advisory
* WHAT...Afternoon high temperatures 95 to 105 degrees at lower
elevations and desert areas. Mild relief at night with low
temperatures in the 60s at lower elevations and upper 40s through
50s in the higher terrain.
* WHERE...Portions of south central and southwest Idaho and nor…
Tomorrow in Boise looks
sunny, with a high of 104°
and an overnight low of 68°.
Rain is unlikely (0% chance).
Winds top out near 10 mph,
and the UV index reaches 7 (high).
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.
Boise weather: 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.
Season by season
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.
Average temperatures in Boise by month
Monthly averages for Boise based on 2015–2024 weather data.
July is the hottest month in Boise, with average highs of 94°F (34°C) and overnight lows near 65°F (18°C). In the past decade the temperature has peaked at 107°F (42°C).
What is the coldest month in Boise?
December is the coldest month, with highs averaging 38°F (4°C) and lows around 25°F (-4°C). The lowest reading in recent years was -10°F (-23°C).
What is the rainiest month in Boise?
December is typically the wettest month, averaging 2.2 inches (56 mm) of precipitation across about 12 days. July is usually the driest.
Does it snow in Boise?
Yes. Boise averages about 18 days of snowfall a year, concentrated November through April.
What is the 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).
How sunny is Boise?
Boise averages 10.0 hours of sunshine per day across the year. July is the sunniest month at about 14.0 hours of sun a day.
Is Boise humid?
Relative humidity in Boise averages about 52% over the year, which feels dry. The most comfortable months tend to fall in the drier part of the year.