Heat stress in Boise
High-desert heat: hot, dry, sun-drenched summer afternoons trending hotter in recent years.
Heat stress is low right now: normal outdoor activity is fine.
Wet-bulb globe temperature via the Liljegren (2008) method. This page is cached and refreshes in the background, so the live badge below can be a few minutes ahead of it.
View Boise on the live mapReading heat stress in Boise
Wet-bulb globe temperature (WBGT) is the heat measure that actually tracks danger to the body. Unlike the plain air temperature on your phone, it folds in humidity, wind, and direct sun: the factors that decide whether your sweat can still cool you. It’s the standard the military, athletic associations, and occupational-safety bodies use to call when outdoor activity is no longer safe.
That matters in Boise because high-desert heat: hot, dry, sun-drenched summer afternoons trending hotter in recent years. The number above is the live outdoor WBGT for the city right now; tap through to the live map to inspect any neighborhood, scrub the forecast hour by hour, and see the 7-day outlook.
How hot Boise usually gets
Across 2015–2024, Boise averaged a 89°F daily high in summer: 53rd hottest of the 174 metros we track, and July is typically the warmest month.
Most of the heat here sits below the extremes: around 55 days a year top 90°F, and only about 11 reach 100°F.
The air is dry, averaging about 32% through summer, so sweat works and the danger is sun load and raw heat rather than mugginess.
A bad day runs well past a normal one, with 107°F recorded against a 89°F summer average.
Daily high temperatures and humidity from ERA5 reanalysis, 2015–2024 (hottest day in the sample: 2021-07-26). These are climate averages for context: the reading at the top of this page is the live one.
For school sports, IHSAA (Idaho High School Activities Association) publishes IHSAA Fall Sports Practice/Safety Model: Heat Stress and Athletic Participation. That document sets no WBGT limits, so no Idaho activity zones appear beside the live reading. The heat-stress guidance on this page applies to anyone outdoors. Our Idaho heat policy page has the details, the source and the date we last checked it.
Heat in Boise: common questions
How hot does it usually get in Boise?
Across 2015–2024, Boise averaged a 89°F daily high through summer, with about 55 days a year at or above 90°F and 11 at or above 100°F. July is typically the hottest month, and the hottest day in that sample reached 107°F. Figures are from ERA5 daily reanalysis.
When is the hottest time of year in Boise?
July has the highest average daily high in Boise. Summer humidity averages only about 32%, so sweat evaporates efficiently: the danger here is sun and raw heat rather than mugginess. Use the forecast on this page to plan around the specific days that matter.
Does Idaho have a heat policy for school sports?
IHSAA (Idaho High School Activities Association) publishes IHSAA Fall Sports Practice/Safety Model: Heat Stress and Athletic Participation. That document sets no WBGT limits, so no Idaho activity zones appear beside the live reading. The heat-stress guidance on this page applies to anyone outdoors. Our WBGT is a modeled estimate rather than an on-site measurement, so check the association's own document for current requirements.
What is the WBGT in Boise right now?
The reading at the top of this page is the current wet-bulb globe temperature for Boise, Idaho, computed from live weather by the Liljegren (2008) method and labeled with how recently it updated. For an exact reading at your own neighborhood, plus an hour-by-hour forecast, open the live map.
Why is WBGT more useful than the temperature for Boise?
Air temperature ignores humidity, wind, and sun: the things that decide whether heat is dangerous. Boise's climate (high-desert heat: hot, dry, sun-drenched summer afternoons trending hotter in recent years.) is exactly why a single "feels-like" or thermometer reading can understate the real risk. WBGT captures all of it in one number.
When is heat most dangerous in Boise?
July is the peak month in Boise, and within a day heat stress is highest in the early-to-mid afternoon when sun load is greatest. About 55 days a year reach 90°F, so most of the risk sits in a handful of afternoons rather than across the whole season. Use the forecast on this page to find the window that works.
Put Boise’s live heat stress on your site
A self-updating WBGT badge for schools, teams, camps, and local sites: it always shows the current reading and links back here.
<iframe src="https://wetbulbtracker.com/embed/boise-id" width="340" height="150" style="border:0" title="Live WBGT: Boise, ID" loading="lazy"></iframe>Paste it into any website. The badge updates itself and links back here. Add ?theme=light for light sites.