Heat stress in San Diego
Marine-moderated and usually comfortable, with occasional humid heat events that catch people off guard.
Light precautions for intense activity. Keep water handy.
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 San Diego on the live mapNo restrictions for healthy people. Drink to thirst, and keep an eye on anyone not yet used to the heat — young children, older adults and anyone unwell feel it sooner.
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 San Diego
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 San Diego because marine-moderated and usually comfortable, with occasional humid heat events that catch people off guard. 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 San Diego usually gets
Across 2015–2024, San Diego averaged a 75°F daily high in summer — among the lower summer highs we track, and August is typically the warmest month.
Humidity is the real story here — summer averages about 77%, so sweat evaporates poorly and heat stress runs well above what the temperature alone suggests.
Daily high temperatures and humidity from ERA5 reanalysis, 2015–2024 (hottest day in the sample: 2020-09-30). These are climate averages for context — the reading at the top of this page is the live one.
Heat in San Diego: common questions
How hot does it usually get in San Diego?
Across 2015–2024, San Diego averaged a 75°F daily high through summer, with about 2 days a year at or above 90°F. August is typically the hottest month, and the hottest day in that sample reached 98°F. Figures are from ERA5 daily reanalysis.
When is the hottest time of year in San Diego?
August has the highest average daily high in San Diego. Humidity is the real story here — summer averages about 77%, so sweat evaporates poorly and heat stress runs well above what the temperature alone suggests. Use the forecast on this page to plan around the specific days that matter.
What is the WBGT in San Diego right now?
The reading at the top of this page is the current wet-bulb globe temperature for San Diego, 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 San Diego?
Air temperature ignores humidity, wind, and sun — the things that decide whether heat is dangerous. San Diego's climate (marine-moderated and usually comfortable, with occasional humid heat events that catch people off guard.) 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 San Diego?
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 San Diego?
Yes. WetBulbTracker is free, needs no account, and works for anywhere on Earth — not just San Diego. You can install it to your home screen and even set heat alerts.
Put San Diego’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/san-diego-ca" width="340" height="150" style="border:0" title="Live WBGT — San Diego, CA" loading="lazy"></iframe>Paste it into any website. The badge updates itself and links back here. Add ?theme=light for light sites.