Heat stress in Surprise
Far-northwest Valley community on the desert's edge, where scorching summer highs and little shade drive heat-stress risk sharply upward.
Limit outdoor exertion. Drink water every 15 minutes and rest in shade.
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 Surprise on the live mapReading heat stress in Surprise
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 Surprise because far-northwest Valley community on the desert's edge, where scorching summer highs and little shade drive heat-stress risk sharply upward. 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 Surprise usually gets
Across 2015–2024, Surprise averaged a 105°F daily high in summer: 8th hottest of the 174 metros we track, and July is typically the warmest month.
Heat here is the default rather than an event: about 97 days a year reach 100°F, and 164 reach 90°F.
The air is dry, averaging about 27% 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 119°F recorded against a 105°F summer average.
Daily high temperatures and humidity from ERA5 reanalysis, 2015–2024 (hottest day in the sample: 2017-06-20). These are climate averages for context: the reading at the top of this page is the live one.
For school sports, AIA (Arizona Interscholastic Association) publishes AIA Policies and Procedures 2026-27, Article 43 Sports Medicine §43.6, which uses wet-bulb globe temperature. Arizona’s activity zones appear beside the live reading in the app.
Heat in Surprise: common questions
How hot does it usually get in Surprise?
Across 2015–2024, Surprise averaged a 105°F daily high through summer, with about 164 days a year at or above 90°F and 97 at or above 100°F. July is typically the hottest month, and the hottest day in that sample reached 119°F. Figures are from ERA5 daily reanalysis.
When is the hottest time of year in Surprise?
July has the highest average daily high in Surprise. Summer humidity averages only about 27%, 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 Arizona have a heat policy for school sports?
AIA (Arizona Interscholastic Association) publishes AIA Policies and Procedures 2026-27, Article 43 Sports Medicine §43.6, which uses wet-bulb globe temperature. Arizona’s activity zones appear beside the live reading in the app. Our WBGT is a modeled estimate rather than the on-site device reading a policy may call for, so check the association's own document for current requirements.
What is the WBGT in Surprise right now?
The reading at the top of this page is the current wet-bulb globe temperature for Surprise, Arizona, 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 Surprise?
Air temperature ignores humidity, wind, and sun: the things that decide whether heat is dangerous. Surprise's climate (far-northwest Valley community on the desert's edge, where scorching summer highs and little shade drive heat-stress risk sharply upward.) 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 Surprise?
July is the peak month in Surprise, and within a day heat stress is highest in the early-to-mid afternoon when sun load is greatest. With roughly 97 days a year above 100°F, the safe window is often early morning rather than merely "not midday". Use the forecast on this page to find the window that works.
Put Surprise’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/surprise-az" width="340" height="150" style="border:0" title="Live WBGT: Surprise, AZ" loading="lazy"></iframe>Paste it into any website. The badge updates itself and links back here. Add ?theme=light for light sites.