Boise, ID Weather
Boise hourly forecast: next 24 hours
Today's high of 76°F (25°C) is about 4°F (2°C) below the typical September high of 80°F (27°C).
Current conditions in detail
Boise weather tomorrow (Wednesday, September 16)
Tomorrow in Boise looks overcast, with a high of 82° and an overnight low of 53°. Rain is unlikely (4% chance). Winds top out near 10 mph, and the UV index reaches 6 (moderate).
Boise 14-day forecast
About the weather in Boise
Seasons are the whole story in Boise. The gap between an average July and an average December is 27°C - big day-to-night temperature swings and modest rainfall - which in practice means 94°F (34°C) afternoons at one end of the calendar and 38°F (4°C) at the other.
Boise weather: quick facts
- Hottest month: July - highs near 94°F (34°C)
- Coldest month: December - highs near 38°F (4°C)
- Decade extremes (2015-2024): 107°F (42°C) high · -10°F (-23°C) low
- Wettest month: December (12 rainy days) · Sunniest: July (14.0 h sun/day)
- Climate type: semi-arid
- Annual swing: 27°C between the average warmest and coolest month · day to night: 12°C
- Snow: about 18 days a year
- Months averaging 30°C or hotter: 2
- Average humidity: 52%
Temperatures through the year
Precipitation concentrates in December - 2.2 inches (56 mm) on 12 days - and thins out by July. December sits at the other end of the year: 38°F (4°C) by day, 25°F (-4°C) at night. Warmth peaks in July: highs of 94°F (34°C), lows of 65°F (18°C). Three of the twelve months pair mild highs with fewer than twelve wet days; the longest unbroken run is September through October.
Rain, sun and snow
Relative humidity averages 52% across the year, drier than all but 8% of the 3496 cities in our dataset. 3 months average under 20 mm of rain, the longest unbroken stretch running July through September. Between the average July and the average December lie 27°C, a wider spread than 92% of the 3496 cities in our dataset. Across the gridded 2015-2024 daily record, the highest daily maximum for this location was 107°F (42°C) and the lowest daily minimum -10°F (-23°C).
Season by season
Spring (March through May)
Spring in Boise stays on the cool side of mild, 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 about 3 snowy days. Daylight is generous - around 10.8 hours of sun a day.
Summer (June through August)
Summer in Boise is hot, with daytime highs averaging 89°F (32°C) and nights around 62°F (17°C); precipitation is sparse, near 1.1 inches (29 mm) for the season. Daylight is generous - around 13.4 hours of sun a day.
Fall (September through November)
Fall runs cool rather than cold here - highs near 65°F (18°C), nights near 43°F (6°C), and rain comes on about 16 days over the three months.
Winter (December through February)
Winter is brisk and cold here - highs near 41°F (5°C), nights near 26°F (-3°C), and rain falls on around 32 of the 90 days, plus about 14 snowy days.
Average temperatures in Boise by month
| 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% |