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Climate in Boise, Idaho: Monthly Weather Averages

By the AverageClimate Editorial Team · Last updated: October 2026

Boise sits at 2,814 feet above sea level, and its climate, as recorded at the Boise Air Terminal, ID station, runs to a yearly mean of 53.2°F. The warmest month is July, averaging 77.3°F with typical highs of 92.7°F; the coldest is December, averaging 32.1°F with lows around 25.4°F. Across a normal year the city receives 11.5 in of precipitation and 17.6 in of snow. The full month-by-month picture below comes from the official 1991–2020 U.S. Climate Normals — the 30-year averages the National Weather Service itself uses — so it describes the Boise climate you should actually plan around, whether you are timing a visit, weighing a move, or just settling an argument about which month is best.

Boise climate month by month

The table below is the complete 1991–2020 normals profile for Boise: average high, average low and mean temperature, rainfall, and snowfall for every month. Read down the Mean column to feel the year's rhythm — Boise's temperature range runs from 32.1°F in December to 77.3°F in July.

How to read the colors:below freezingcoldcoolmildwarmhot. Bands are colored by each cell's own temperature, so a whole year reads at a glance.

Boise through the seasons

Winter in Boise averages highs of 38.8–46.0°F and lows of 25.4–29.0°F, a seasonal mean of 33.9°F. The three months together bring 4.0 in of precipitation — about 34% of the city's yearly total — with December the wettest of the three at 1.54 in. Snowfall averages 14.2 in over the season, most of it in December (5.6 in). It is a genuinely cold season — heavy coats, freezing nights, and the year's most changeable weather — without being locked below freezing around the clock.

Spring in Boise averages highs of 55.5–72.3°F and lows of 34.9–47.5°F, a seasonal mean of 52.0°F. The three months together bring 4.0 in of precipitation — about 35% of the city's yearly total — with May the wettest of the three at 1.45 in. Snowfall averages 1.3 in over the season, most of it in March (1.2 in). The season is a transition: the average temperature climbs 14.7°F from March to May, and by late spring Boise is firmly into mild territory.

Summer in Boise averages highs of 81.4–92.7°F and lows of 54.1–61.9°F, a seasonal mean of 73.6°F. The three months together bring 1.1 in of precipitation — about 10% of the city's yearly total — with June the wettest of the three at 0.75 in. Summers are hot in the classic sense — most afternoons reach the 90s, and shade, water, and air conditioning shape the daily routine.

Fall in Boise averages highs of 48.8–80.0°F and lows of 31.7–52.6°F, a seasonal mean of 53.3°F. The three months together bring 2.4 in of precipitation — about 21% of the city's yearly total — with November the wettest of the three at 1.18 in. Snowfall averages 2.1 in over the season, most of it in November (2.0 in). Temperatures ease off through the season — the monthly mean drops 26.0°F from September to November — and fall is when Boise's weather turns crisp and dry, with the first freezes arriving by November.

Best and worst months to visit Boise

Ranking every month by its normals — mild mean temperatures score best, heavy rain and snow count against — the most comfortable months to visit Boise are:

JuneAugustSeptember

June leads the list: average highs of 81.4°F, lows of 54.1°F, and 0.75 in of rain, with snow a non-factor at 0.0 in. The other picks, August and September, offer the same balance in Boise's mild stretch of the year. At the other end, December is usually the month to avoid — deep-winter cold, with a mean temperature of 32.1°F and 1.54 in of precipitation plus 5.6 in of snow.

How Boise compares

Across the 114 cities in our dataset, the typical city averages 57.8°F for the year and 35.7 in of precipitation. Boise runs 4.6°F cooler than that typical city and drier by 24.1 in a year, ranking #73 of 114 for annual warmth and #103 of 114 for precipitation (wettest first). Its year-round temperature swing — warmest month minus coldest — is 45.2°F, which puts it in the strongly continental, four-real-seasons camp.

Planning notes for Boise

For anyone relocating: average overnight lows drop below freezing in 4 months (January, February, November, December), so heating, winter tires, and pipe protection are real seasonal concerns; 2 months average highs of 90°F or more, making air conditioning a core cost of summer life; days and nights differ by 22.3°F on average — a big desert-style swing that rewards dressing in layers year-round; 5 months of the year average between 55°F and 80°F, the band most people find comfortable without heating or cooling. Those four facts, all straight from the normals table above, shape everything from a Boise wardrobe to its utility bills.

Boise climate FAQ

Source: 1991–2020 U.S. Climate Normals, NOAA National Centers for Environmental Information (NCEI) — ncei.noaa.gov. Station: Boise Air Terminal, ID (USW00024131), elevation 2,814 ft. Figures checked October 2026.