ID · climate averages
Boise Weather by Month
These are climate averages, not a forecast. Station Boise Air Terminal (USW00024131), 2.4 miles from downtown, elevation 2814 ft.
Boise's warmest month is July (avg high 92.7°F), coldest is December (avg low 25.4°F) and wettest is December (1.54 in), per NOAA 1991–2020 climate normals.
- Warmest high July 92.7°F
- Coldest low December 25.4°F
- Wettest month December 1.54 in
- Year of rain 12 months 11.51 in
Monthly Averages
Boise's 12 monthly precipitation normals add up to 11.51 inches a year.
August is the driest month, with a precipitation normal of 0.17 inches.
January, February, March, November and December are the months with a snowfall normal above 0.1 inch, and they sum to 17.4 inches.
Boise averages 89.2 days a year with at least 0.01 inch of precipitation.
| Month | Avg high | Avg low | Precipitation | Days ≥ 0.01 in | Snow |
|---|---|---|---|---|---|
| January | 38.8°F | 25.5°F | 1.41 in | 11.1 | 5.3 in |
| February | 46.0°F | 29.0°F | 1.00 in | 9.1 | 3.3 in |
| March | 55.5°F | 34.9°F | 1.33 in | 10.1 | 1.2 in |
| April | 62.3°F | 39.6°F | 1.23 in | 9.2 | 0.1 in |
| May | 72.3°F | 47.5°F | 1.45 in | 8.4 | 0.0 in |
| June | 81.4°F | 54.1°F | 0.75 in | 5.3 | 0.0 in |
| July | 92.7°F | 61.9°F | 0.21 in | 2.3 | 0.0 in |
| August | 90.7°F | 60.8°F | 0.17 in | 2.1 | 0.0 in |
| September | 80.0°F | 52.6°F | 0.43 in | 3.9 | 0.0 in |
| October | 64.8°F | 41.5°F | 0.81 in | 6.0 | 0.1 in |
| November | 48.8°F | 31.7°F | 1.18 in | 9.7 | 2.0 in |
| December | 38.8°F | 25.4°F | 1.54 in | 12.0 | 5.6 in |
Warmest, Coldest and Wettest Months
The warmest month is July, with an average high of 92.7°F.
The coldest month is December, with an average low of 25.4°F.
The wettest month is December, at 1.54 inches of precipitation over about 12.0 days.
July and August are the only months in Boise with an average high of at least 90°F.
The range from the lowest average low to the highest average high in Boise is 67.3°F.
In July, the average high in Boise is 30.8°F above the average low.
Best Months to Visit Boise for Weather
June and September meet the weather rule on this page: an average high from 65 to 85°F and precipitation below 0.96 inches.
The rule keeps a month when the average high is from 65 to 85°F and precipitation is below 0.96 inches, the mean of the twelve monthly precipitation normals.
- June · 81.4°F
- September · 80.0°F
About This Data
Source: NOAA National Centers for Environmental Information (NCEI), U.S. Climate Normals 1991–2020. Station: BOISE AIR TERMINAL (USW00024131), 2.4 mi from downtown, elevation 2814 ft. Climate normals are 30-year averages, not forecasts. MonthSky is not affiliated with NOAA.
Palecki, Michael; Durre, Imke; Applequist, Scott; Arguez, Anthony; Lawrimore, Jay (2021). U.S. Climate Normals 2020: U.S. Monthly Climate Normals (1991-2020). NOAA National Centers for Environmental Information. Dataset. https://doi.org/10.25921/wck8-er13. Accessed 2026-10-21.
U.S. Government work.
NOAA and NCEI cannot provide any warranty as to the accuracy, reliability, or completeness of furnished data. Users assume responsibility to determine the usability of these data. The user is responsible for the results of any application of this data for other than its intended purpose.
NOAA and NCEI make no warranty, expressed or implied, regarding these data, nor does the fact of distribution constitute such a warranty. NOAA and NCEI cannot assume liability for any damages caused by any errors or omissions in these data. If appropriate, NCEI can only certify that the data it distributes are an authentic copy of the records that were accepted for inclusion in the NCEI archives.
These pages are built automatically from public NOAA data.
U.S. Monthly Climate Normals (1991-2020) dataset
NCEI dataset landing page for the monthly normals
FAQ
What is the hottest month in Boise?
July is the warmest, with an average high of 92.7°F.
What is the wettest month in Boise?
December is the wettest, at 1.54 inches over about 12.0 days.
How many rainy days does Boise get a year?
The monthly counts of days with at least 0.01 inch of precipitation add up to 89.2 days.
When is the best time to visit Boise for weather?
June and September meet the rule used on this page: average high from 65 to 85°F and precipitation below the monthly mean of 0.96 inches.