Idaho local data guide

Boise, Idaho: Monthly Climate Normals

Boise, Idaho, features a cold semi-arid climate, characterized by distinct seasonal variations with hot, dry summers and cold winters. The data provided here represents the official 1991–2020 climate normals recorded at the Boise Airport, which serve as long-term averages rather than real-time daily weather forecasts.

Updated with grounded research as of 2026-07-21.

The short answer

Boise experiences significant seasonal temperature contrasts, with average summer highs often reaching into the 90s°F and winter lows frequently dropping near or below freezing. The region is semi-arid, receiving approximately 11–12 inches of annual precipitation, which is distributed throughout the year but generally lighter during the peak of summer.

Key facts

Hottest Month (Avg. High)
July (~92°F)
Coldest Month (Avg. Low)
January (~25°F)
Climate Normal Period
1991–2020
Average Annual Precipitation
Approximately 11–12 inches

Temperature and Seasonal Trends

Boise’s inland location creates a climate where temperatures shift notably between seasons. While summer afternoons are typically hot and dry—often peaking in July—the humidity remains relatively low, which many residents find comfortable.

  • Summers: Hot, dry conditions are the norm, with July and August seeing the highest average temperatures.
  • Winters: Cold temperatures persist, with January typically being the coldest month of the year.
  • Temperature Variations: Diurnal temperature swings are common due to the semi-arid environment.

Precipitation and Humidity

Annual precipitation in Boise is relatively low, consistent with its semi-arid classification. Most moisture occurs in the form of rain or snow during the cooler months, while the summer season is characterized by minimal rainfall.

  • Annual Average: Total precipitation typically measures between 11 and 12 inches annually at the Boise Airport station.
  • Seasonal Distribution: Precipitation is spread across the year, though summer months remain notably dry.

Using Climate Normals for Planning

Climate normals are essential tools for long-term planning, such as estimating utility costs, scheduling outdoor projects, or planning relocation logistics. These figures are calculated over a 30-year period to smooth out year-to-year weather anomalies.

  • Reference Point: Normals provide a baseline to compare against current daily or monthly observations.
  • Limitations: These averages do not predict extreme weather events or specific variations for any single year.

Common questions

Where is this weather data collected?

The climate data presented here is measured at the Boise Airport station. Please note that conditions may differ significantly in the surrounding foothills or at higher elevations due to changes in topography.

How do I check the current daily weather forecast?

For up-to-date, day-to-day weather forecasts and current alerts, please visit the official National Weather Service Boise office website.

Related Idaho questions

  • How to access current daily climate reports for Boise?
  • What is the average snowfall in Boise by month?
  • Where can I find historical weather data for Boise?

Sources and verification