Boise, Idaho, features a semi-arid continental climate with four distinct seasons. Summers are hot, dry, and sunny, while winters are cold, occasionally snowy, and partly cloudy. With low humidity, over 200 days of sunshine per year, and mild shoulder seasons, Boise offers a dynamic climate ideal for outdoor activities, festivals, and exploring the scenic Treasure Valley.
The best times to travel section shows how the months compare for a visit, so you can find the time of year that fits what you want to do.
Background colours of the months:
The colour shows the typical temperature: yellow (hot), green (mild) and blue (cold). How strong the colour is shows the travel season: full colour means high season, soft colour means shoulder season and soft-striped means off season.
Weather symbols:
Each month has one symbol showing what the weather is typically like, such as hot and sunny, freezing or a rainy or snowy season. Use them to quickly spot months that match the weather you want, or to avoid the ones that don't.
Crowdedness:
The people icon shows how busy the place usually is. The more people, the more crowded it gets.
Additional notes:
The grey info boxes point out special things worth knowing, like recurring weather issues or seasonal events.
Boise’s climate is shaped by its high-desert location in the Treasure Valley, resulting in significant seasonal contrasts and generally mild, dry weather. Summers (June–August) are hot and dry, with average highs of 32°C in July and August, and cool nights around 14°C. Humidity is low, typically 30–40%, and rainfall is scarce, with less than 7 mm per month in peak summer. Sunshine is abundant, with up to 13 hours daily, and the city enjoys over 200 sunny days each year. Occasional afternoon thunderstorms provide brief relief from the heat, and evenings cool off quickly.
Winters (December–February) are cold and partly cloudy, with average highs of 3–7°C and lows dipping to –6°C. Snowfall averages 19–20 inches (48–51 cm) per year, but snow rarely lingers long in the city. Most winter precipitation falls as rain or light snow, and freezing rain is rare. The surrounding mountains receive much heavier snowfall, making Boise a gateway for winter sports. Spring (March–May) and autumn (September–November) are transitional, with mild to warm days (12–25°C), chilly nights, and variable weather. Spring brings blooming wildflowers and the city’s greenbelt comes alive, while fall is known for colourful foliage and crisp, clear days. Winds are generally light to moderate (10–15 km/h), but can be brisk during storms, especially in spring and autumn. Annual precipitation is low, averaging just 298 mm (11.7 inches), with most rain falling in spring. Boise’s climate supports a long growing season and a vibrant outdoor lifestyle.
| Average climate data for Boise, United States | |||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Month | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Year |
| Average maximum temperature (°C) | 2 | 4 | 9 | 14 | 19 | 24 | 31 | 30 | 24 | 15 | 8 | 1 | 31 |
| Average minimum temperature (°C) | -5 | -2 | 1 | 3 | 7 | 12 | 16 | 16 | 12 | 6 | -0 | -5 | -5 |
| Average precipitation (mm) | 52 | 49 | 56 | 33 | 37 | 26 | 5 | 6 | 10 | 26 | 30 | 53 | 384 |
| Average rainfall days (days) | 11 | 12 | 16 | 14 | 11 | 9 | 4 | 5 | 7 | 9 | 10 | 10 | 117 |
| Average snowfall (mm) | 165 | 123 | 38 | 2 | 0 | 0 | 0 | 0 | 0 | 0 | 44 | 167 | 539 |
| Average snowfall days (days) | 8 | 7 | 3 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 3 | 9 | 31 |
| Average relative humidity (%) | 79 | 76 | 68 | 57 | 52 | 44 | 30 | 32 | 38 | 52 | 64 | 79 | 56 |
| Average wind speed (km/h) | 8 | 10 | 11 | 11 | 10 | 10 | 9 | 9 | 9 | 9 | 10 | 9 | 10 |
| Average daily daylight hours (h) | 9 | 10 | 12 | 13 | 14 | 15 | 15 | 13 | 12 | 11 | 9 | 9 | 12 |
| Average daily sunshine hours (h) | 5 | 7 | 7 | 9 | 10 | 11 | 12 | 11 | 9 | 7 | 6 | 5 | 8 |
| Average cloud coverage (%) | 40 | 41 | 39 | 30 | 24 | 17 | 9 | 8 | 15 | 22 | 32 | 43 | 27 |
| Average UV index | 2 | 2 | 3 | 3 | 5 | 6 | 7 | 5 | 4 | 3 | 2 | 2 | 4 |
The best time to visit Boise is in spring (March–May) and fall (September–October), when temperatures are mild, rainfall is moderate, and the city’s parks and trails are at their most vibrant. These seasons offer ideal conditions for hiking, biking, festivals, and exploring both urban and natural attractions.
The least favourable time to visit Boise is in the peak of summer (late June–August), when temperatures can exceed 32°C and the dry heat can be intense for outdoor activities. However, summer is still popular for river activities and festivals. Winter (December–February) is cold and can be snowy, but is ideal for nearby skiing.
Boise has a semi-arid continental climate with hot, dry summers, cold winters, and mild, sunny spring and autumn seasons. The city receives low annual rainfall and enjoys over 200 days of sunshine each year.
Spring (March–May) and fall (September–October) are the best times to visit Boise, offering mild temperatures, moderate rainfall, and vibrant outdoor scenery. These seasons are ideal for hiking, biking, and festivals.
Yes, Boise receives about 19–20 inches (48–51 cm) of snow per year, mostly in winter. Snow events are usually light and short-lived in the city, but the nearby mountains get much heavier snowfall for winter sports.
Summers in Boise are hot and dry, with average highs of 32°C in July and August. Nights cool off quickly, and humidity is low, making the heat more comfortable than in more humid regions.
Boise receives an average of 298 mm (11.7 inches) of precipitation annually, with most rain falling in spring. Summers are very dry, with little rainfall and abundant sunshine.
Pack light, breathable clothing and sun protection for summer, and warm layers for winter. In spring and autumn, bring layers for variable temperatures and a rain jacket for occasional showers or breezy days.
Yes, Boise is great for outdoor activities throughout the year. Spring and autumn are best for hiking and biking, summer is ideal for river and sun activities, and winter offers access to nearby ski resorts.
The warmest month, with the highest average maximum temperature, is July (31 °C). The month with the lowest average maximum temperature is December (1.4 °C). Overall, the average maximum temperature over the whole year is 15.2 °C.
The month with the highest average minimum temperature is August (16.2 °C). The coldest month, with the lowest average minimum temperature, is December (-5 °C). Overall, the average minimum temperature over the whole year is 5.1 °C.
The wettest month, with the highest amount of precipitation, is March (56.4 mm). The driest month, with the least amount of precipitation, is July (5 mm). Over the whole year there are 384.4 mm of rainfall on average.
The month with the most days of rain is March (16.2 days). The month with the fewest days of rain is July (4.5 days). Over the whole year there are 117.1 days of rain on average.
The month with the most snowfall is December (166.7 mm). The months with the least snowfall are May, June, July, August, September and October (0 mm). Over the whole year there are 538.7 mm of snowfall on average.
The month with the most days of snowfall is December (9.2 days). The months with the fewest days of snowfall are June, July and September (0 days). Over the whole year there are 31.3 days of snowfall on average.
The month with the highest average relative humidity is January (79.4 %). The month with the lowest average relative humidity is July (30.2 %). The overall average relative humidity over the whole year is 56.1 %.
The windiest month, with the highest average wind speed, is April (11.3 km/h). The calmest month, with the lowest average wind speed, is January (8.4 km/h). The overall average wind speed over the whole year is 9.5 km/h.
The month with the cloudiest skies, so the highest cloud coverage, is December (43.2 %). The month with the clearest skies, so the lowest cloud coverage, is August (8.4 %). Over the whole year there is an average cloud coverage of 26.7 %.
The month with the longest days, so the most daylight, is June (Average daylight: 15 h). The month with the shortest days, so the least daylight, is December (Average daylight: 9 h). Over the whole year there are 11.9 h of daylight per day on average.
The month with the most sunshine per day is July (Average sunshine: 11.9 h). The month with the least sunshine per day is January (Average sunshine: 5.1 h). Over the whole year there are 8.3 h of sunlight per day on average.
The month with the highest average UV index is July (UV index: 7). The months with the lowest average UV index are January, February, November and December (UV index: 2). Over the whole year the average UV index is 3.7.
