Heat stress in Fresno
Among California's hottest cities, with prolonged triple-digit Central Valley heat waves.
Reduce exertion and hydrate frequently. Take regular shade breaks.
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 Fresno on the live mapComfortable in short stretches. Take a shaded break each hour of activity, drink before you feel thirsty, and move anything strenuous to the morning. Never leave children or pets in a parked car.
Screening guidance from ACGIH TLV, GHSA/KSI/NATA, and TB MED 507. WBGT is a composite index, not air temperature. These are acclimatized-population defaults — the unacclimatized, older, ill, or those on certain medications are at higher risk. Not a substitute for a required on-site WBGT reading or your employer / league / command policy.
Reading heat stress in Fresno
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 Fresno because among California's hottest cities, with prolonged triple-digit Central Valley heat waves. 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 Fresno usually gets
Across 2015–2024, Fresno averaged a 100°F daily high in summer — higher than most cities we track, and July is typically the warmest month.
Summer humidity averages only about 29%, so sweat evaporates efficiently — the danger here is sun and raw heat rather than mugginess.
Daily high temperatures and humidity from ERA5 reanalysis, 2015–2024 (hottest day in the sample: 2024-07-07). These are climate averages for context — the reading at the top of this page is the live one.
Heat in Fresno: common questions
How hot does it usually get in Fresno?
Across 2015–2024, Fresno averaged a 100°F daily high through summer, with about 120 days a year at or above 90°F and 61 at or above 100°F. July is typically the hottest month, and the hottest day in that sample reached 118°F. Figures are from ERA5 daily reanalysis.
When is the hottest time of year in Fresno?
July has the highest average daily high in Fresno. Summer humidity averages only about 29%, 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.
What is the WBGT in Fresno right now?
The reading at the top of this page is the current wet-bulb globe temperature for Fresno, California, computed from live weather by the Liljegren (2008) method and labelled with how recently it updated. For an exact reading at your own neighbourhood, plus an hour-by-hour forecast, open the live map.
Why is WBGT more useful than the temperature for Fresno?
Air temperature ignores humidity, wind, and sun — the things that decide whether heat is dangerous. Fresno's climate (among California's hottest cities, with prolonged triple-digit Central Valley heat waves.) 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 Fresno?
Heat stress typically peaks in the early-to-mid afternoon, when sun load is highest. Plan strenuous outdoor activity for early morning or evening, hydrate ahead of time, and use the forecast scrubber on the live map to find the safest window.
Is WetBulbTracker free to use for Fresno?
Yes. WetBulbTracker is free, needs no account, and works for anywhere on Earth — not just Fresno. You can install it to your home screen and even set heat alerts.
Put Fresno’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/fresno-ca" width="340" height="150" style="border:0" title="Live WBGT — Fresno, CA" loading="lazy"></iframe>Paste it into any website. The badge updates itself and links back here. Add ?theme=light for light sites.