Boise climate
Boise (Idaho, United States) has a hot-summer continental (dry summer) climate (Köppen Dsa). The average temperature over the year is 12 °C54 °F, and about 389 mm15 in of precipitation falls in an average year.
Temperature by month
Precipitation by month
Boise climate table
| Month | High °C°F | Low °C°F | Mean °C°F | Precip. mmin |
|---|---|---|---|---|
| Jan | 439 | −425 | 032 | 512.0 |
| Feb | 744 | −228 | 236 | 361.4 |
| Mar | 1254 | 134 | 744 | 471.9 |
| Apr | 1662 | 439 | 1050 | 351.4 |
| May | 2373 | 948 | 1660 | 381.5 |
| Jun | 2883 | 1356 | 2170 | 230.9 |
| Jul | 3595 | 1966 | 2781 | 70.3 |
| Aug | 3493 | 1865 | 2679 | 70.3 |
| Sep | 2882 | 1355 | 2069 | 140.5 |
| Oct | 1865 | 643 | 1254 | 271.1 |
| Nov | 1050 | 032 | 541 | 401.6 |
| Dec | 439 | −425 | 032 | 652.6 |
| Year | 3595 | −425 | 1254 | 38915 |
“Year” row: highest monthly high, lowest monthly low, annual mean and annual total.
| Month | Humid. | Cloud | Solar | Daylight |
|---|---|---|---|---|
| Jan | 81% | 72% | 1.7 | 9:17 |
| Feb | 73% | 67% | 2.7 | 10:26 |
| Mar | 65% | 66% | 4.0 | 11:48 |
| Apr | 58% | 57% | 5.5 | 13:22 |
| May | 52% | 53% | 6.7 | 14:42 |
| Jun | 44% | 41% | 7.5 | 15:25 |
| Jul | 32% | 26% | 7.7 | 15:07 |
| Aug | 29% | 29% | 6.7 | 13:58 |
| Sep | 34% | 33% | 5.2 | 12:26 |
| Oct | 49% | 47% | 3.5 | 10:55 |
| Nov | 64% | 63% | 2.1 | 9:36 |
| Dec | 78% | 73% | 1.4 | 8:57 |
Humid. = average relative humidity at 2 m; cloud = average cloud amount; solar = average daily solar energy reaching the ground in kWh/m² (all-sky); daylight in hours:minutes, calculated for the 15th of each month.
What the climate of Boise is like
The warmest month is July, with an average high of 35 °C95 °F and a low of 19 °C66 °F. The coldest is January, when highs average 4 °C39 °F and lows −4 °C25 °F. Seasons are strongly marked: the warmest month is on average 27.4 °C49.3 °F warmer than the coldest.
It is dry, with about 389 mm15 in of precipitation per year. The wettest three-month stretch is November–January, which brings 40% of the annual total. Months with less than 20 mm0.8 in on average: July–September. The wettest month is December (65 mm2.6 in), the driest is July (7 mm0.3 in).
Relative humidity ranges from 29% in August to 81% in January. The clearest skies (lowest average cloud amount, 26%) are typical of July. Average wind speed near the ground ranges from 7 km/h (4 mph) in September to 9 km/h (5 mph) in April. Daylight lasts from about 8.9 hours in December to 15.4 hours in June.
A lasting snow cover is typical in December–February, when the average snow depth in the reanalysis exceeds 10 cm (deepest in January, about 18 cm).
Best time to visit Boise
Based on these averages, the most comfortable months for sightseeing and outdoor activities are May and June and September and October: average highs of 18 °C65 °F to 28 °C83 °F with 14 mm0.5 in to 38 mm1.5 in of precipitation per month.
The most challenging month is December, which is cold, with average highs of 4 °C39 °F.
Comfort score: months are ranked by how close they come to an average high of 21–28 °C (70–82 °F), lows above 5 °C (41 °F), little precipitation and moderate humidity. The best-ranked months of each place are recommended, even where none meets all of these. These are general rules of thumb applied to long-term averages.
What to pack for Boise
- Winter (December–February) — highs 439 to 7 °C44 °F, lows −425 to −2 °C28 °F, about 51 mm2.0 in of precipitation a month. Pack a warm coat, layers and closed shoes and shoes with good grip, as frost is common.
- Spring (March–May) — highs 1254 to 23 °C73 °F, lows 134 to 9 °C48 °F, about 40 mm1.6 in of precipitation a month. Pack long sleeves, a sweater and a medium jacket and an extra layer for the cooler mornings and evenings.
- Summer (June–August) — highs 2883 to 35 °C95 °F, lows 1356 to 19 °C66 °F, about 12 mm0.5 in of precipitation a month. Pack very light, breathable clothing, a sun hat and plenty of water and an extra layer for the cooler mornings and evenings.
- Autumn (September–November) — highs 1050 to 28 °C82 °F, lows 032 to 13 °C55 °F, about 27 mm1.1 in of precipitation a month. Pack light layers — T-shirts plus a light sweater or jacket and an extra layer for the cooler mornings and evenings.
How Boise compares
Compared with Tri-Cities, about 376 km to the northwest, Boise is on average 1.4 °C2.6 °F cooler and receives 40% more precipitation (389 mm15 in vs 278 mm11 in). The difference is largest in January (3 °C5.3 °F cooler).
Of the 222 places in the United States covered by World Climates, Boise is the 149th warmest by annual mean temperature and the 192nd wettest by annual precipitation. See all of them on the United States climate page.
Places in other countries with the most similar temperature and rainfall pattern: Konya (Turkey, Csa), Kırşehir (Turkey, BSk) and Aksaray (Turkey, BSk).
Nearby places
- Pocatello 315 km · 9 °C49 °F · 411 mm16 in
- Tri-Cities 376 km · 14 °C57 °F · 278 mm11 in
- Spokane 460 km · 9 °C49 °F · 552 mm22 in
- West Valley City 475 km · 12 °C54 °F · 542 mm21 in
- Salt Lake City 476 km · 11 °C52 °F · 543 mm21 in
- West Jordan 485 km · 12 °C54 °F · 542 mm21 in
- Provo 531 km · 12 °C54 °F · 468 mm18 in
- Reno 544 km · 11 °C53 °F · 534 mm21 in
Frequently asked questions
What is the warmest month in Boise?
July is the warmest month in Boise, with an average high of 35 °C (95 °F) and an average low of 19 °C (66 °F).
What is the coldest month in Boise?
January is the coldest month, with an average high of 4 °C (39 °F) and an average low of -4 °C (25 °F).
When does it rain the most in Boise?
December is the wettest month with about 65 mm (2.6 in) of precipitation; July is the driest with about 7 mm (0.3 in).
What is the best time to visit Boise?
Judging by long-term averages, the most comfortable months are May and June and September and October.
About this data
All figures are 25-year averages (January 2001 – December 2025) from the NASA POWER project. Temperature, humidity, wind and precipitation come from the MERRA-2 reanalysis (precipitation is the bias-corrected MERRA-2 product), cloud and solar values from CERES satellite data. They describe a grid cell of roughly 50–70 km, not a single weather station, so they can differ from airport records — most of all on coasts, in mountains and for rainfall. Average highs and lows are the monthly mean temperature plus/minus half of the average daily temperature range. Counts of rainy days are not part of this dataset.
The grid cell’s average elevation is 1,055 m, while Boise lies at about 823 m. Temperatures on this page were therefore adjusted by +1.5 °C2.7 °F using the standard lapse rate of 6.5 °C per 1,000 m.