Idaho local data guide

Average Summer Temperature in Boise, Idaho

Boise, Idaho, features a semi-arid climate known for hot, dry summers where daily high temperatures frequently reach the 80s and 90s°F. July is historically the warmest month of the year, typically experiencing high temperatures ranging from 90°F to 92°F.

Updated with grounded research as of 2026-10-08.

The short answer

During the summer months in Boise, Idaho—defined generally as June through August—residents experience a semi-arid climate characterized by hot, dry days and relatively cool nights. July serves as the peak of the summer heat, with average high temperatures typically settling between 90°F and 92°F.

Key facts

Typical July High Temperature
90°F to 92°F
Summer Climate Characterization
Hot and dry with low precipitation

Temperature Patterns

Boise's geographical position in the Treasure Valley contributes to distinct seasonal shifts. Summers are consistently dry, with precipitation levels remaining very low between June and August. While daytime highs often climb into the 80s and 90s°F, the semi-arid environment frequently allows for significant cooling after sunset, providing a reprieve from the afternoon peak heat.

Seasonal Expectations for Residents

For those relocating or planning a move, it is useful to note that Boise experiences significant diurnal temperature variation. This means that while afternoons can be quite warm, mornings and evenings are often temperate. This cycle is a hallmark of the high-desert environment surrounding the city.

Climatological Context

Weather data in the Treasure Valley is collected by the National Weather Service (NWS) Boise office. These long-term averages reflect the expected baseline for the region. However, Boise can experience periodic heat waves where temperatures exceed these historical averages, as well as cooler-than-average seasonal trends.

Common questions

Does Boise experience 100-degree days?

Yes, it is not uncommon for Boise to experience days where temperatures reach or exceed 100°F during the peak of summer, particularly in July and August, though these days remain outliers compared to the typical 90-degree average.

Is the summer humidity high in Boise?

No, Boise summers are characterized by very low humidity. The region's semi-arid climate means that the heat is typically described as 'dry heat,' which feels distinctly different from the high-humidity summers found in the eastern or southern United States.

Related Idaho questions

  • What is the average annual precipitation in Boise, Idaho?
  • What are the typical winter temperatures in Boise?
  • How does the high-desert climate impact home cooling needs in Boise?

Sources and verification