Boise weather in January
January in Boise: cold, a little rain, with clean air — a fair time to visit.
Updated September 2026 · climate normals from ERA5 reanalysis
#11 of 12 months in Boise · #1116 of 1413 destinations to visit in January · comfort 51/100 (tier D)
- Days
- 5°C
- Nights
- -3°C
- Wet days
- 9
- Sun
- 6.5 h
- Humidity
- 75%
- Daylight
- 9 h
Traveller notes on Boise in January
Other months in Boise
Forum posters describe March in Boise as genuinely transitional - it could feel like winter or like spring, sometimes both within the same day. Posters citing a mid-March spring break stretch reported daytime highs typically in the low 60sF with nighttime lows in the 30sF, alongside spring flowers and greenery starting to appear. Posters discussing wintry conditions that occasionally linger into late February or early March are consistent that any snow or cold snap this late in the season tends to resolve within a day or two rather than sticking around. Posters generally rate March as a genuinely mixed early-spring month for Boise, mild afternoons and chilly mornings the reliable pattern, with real day-to-day variability still worth planning around.
Forum regulars consistently pick September as prime time: mid-month temperatures run about 10 degrees cooler than late August (roughly 65F vs 75F), so you still get long warm days and comfortable nights without August's peak heat and fire risk. One poster's blunt reasoning: it's hot in August with a real chance of wildfire smoke, so September is when 'most tourists are gone and locals have their place back' - you also land right in the run of outdoor events like Jazz on the Grove and the weekly Alive After Five series. Worth a heads-up regardless: wildland fire smoke is possible in September, not guaranteed, but common enough that forum regulars flag it every year.
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Boise climate normals — January
Monthly averages from ERA5 reanalysis. AQI is the mean US Air Quality Index for the month.
Crowds in Boise in January
How busy the place itself is — school and mass holidays, the months an editor tagged, and how sought-after the weather makes them. Never part of the comfort score.
Peak crowdsChristmas and New Year, Winter / Christmas break in United States, school holidays in 2 of the markets that fill it(estimated)
Peak crowdsBusyShoulder seasonQuiet
Best months for Boise's weather
Ranked by this destination's own climate comfort score across the year — a different thing from how busy it gets (see Crowds above).
Toughest weatherBoise's best weather comes in May, June and September — separate windows, not one continuous season.
January coincides with Winter inversion.
Best weatherFair weatherToughest weather
What's on in Boise in January
Recurring seasonal events, natural spectacles, closures and holidays — curated and sourced.
- Hazard
Winter inversion
15 Nov – 15 Feb · usuallyWinter smogCold air pools in the U-shaped valley under a warm lid and the wood smoke and traffic exhaust stay with it, sometimes for weeks. Drive twenty minutes up into the foothills and you come out above it into sunshine. Source ↗
- Holiday
Christmas and New Year
24 Dec – 1 JanChristmas & New YearClosuresCrowdedChristmas Day and New Year's Day are federal holidays: on 25 December most shops, museums and many restaurants close, and airports stay busy through the week between as families travel. New Year's Eve fills bars and restaurants, many at set-menu prices. Source ↗
Nearby, and something's on
Within 300 km of Boise — a day trip or a short hop — with something on this month. Never part of the comfort score.
Where is Boise?
Boise in January — FAQ
- Is January a good time to visit Boise?
- January in Boise: cold, a little rain, with clean air — a fair time to visit. It ranks #11 of 12 months for Boise on SeasonMap's comfort score (51/100).
- What is the weather like in Boise in January?
- In January, Boise averages a daily high of 4.8°C and a low of -3.4°C, with about 38.1 mm of rain over roughly 8.5 rainy days.
- What is the air quality in Boise in January?
- Boise has a mean US Air Quality Index of about 33 in January.
- Does it snow in Boise in January?
- Boise sees roughly 16.7 cm of snowfall in January.
Within 300 km: Sun Valley's Ski season around 26 Nov – 18 Apr.