Heat stress in Washington
Famously swampy summers: high humidity and urban heat drive sustained heat stress.
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 Washington on the live mapReading heat stress in Washington
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 Washington because famously swampy summers: high humidity and urban heat drive sustained heat stress. 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 Washington usually gets
Across 2015–2024, Washington averaged a 86°F daily high in summer: 93rd hottest of the 174 metros we track, and July is typically the warmest month.
Heat arrives in bursts here rather than settling in, with only about 26 days a year at or above 90°F.
Humidity is the real story: summer averages about 72%, so sweat evaporates poorly and heat stress runs well above what a 86°F afternoon suggests.
A bad day runs well past a normal one, with 101°F recorded against a 86°F summer average.
Daily high temperatures and humidity from ERA5 reanalysis, 2015–2024 (hottest day in the sample: 2023-07-29). These are climate averages for context: the reading at the top of this page is the live one.
For school sports, DCSAA (District of Columbia State Athletic Association) publishes DCSAA 2026-27 Member Handbook §X.B: WBGT Environmental Monitoring, WBGT Reading / Activity Guidelines table (printed p. 39), which uses wet-bulb globe temperature. District of Columbia’s activity zones appear beside the live reading in the app. Our District of Columbia heat policy page has the details, the source and the date we last checked it.
Heat in Washington: common questions
How hot does it usually get in Washington?
Across 2015–2024, Washington averaged a 86°F daily high through summer, with about 26 days a year at or above 90°F. July is typically the hottest month, and the hottest day in that sample reached 101°F. Figures are from ERA5 daily reanalysis.
When is the hottest time of year in Washington?
July has the highest average daily high in Washington. Humidity is the real story here: summer averages about 72%, 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.
Does District of Columbia have a heat policy for school sports?
DCSAA (District of Columbia State Athletic Association) publishes DCSAA 2026-27 Member Handbook §X.B: WBGT Environmental Monitoring, WBGT Reading / Activity Guidelines table (printed p. 39), which uses wet-bulb globe temperature. District of Columbia’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 Washington right now?
The reading at the top of this page is the current wet-bulb globe temperature for Washington, District of Columbia, 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 Washington?
Air temperature ignores humidity, wind, and sun: the things that decide whether heat is dangerous. Washington's climate (famously swampy summers: high humidity and urban heat drive sustained heat stress.) 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 Washington?
July is the peak month in Washington, and within a day heat stress is highest in the early-to-mid afternoon when sun load is greatest. Dangerous days are uncommon here, which is its own hazard: 26 days a year reach 90°F, and people are least acclimatized when they arrive. Use the forecast on this page to find the window that works.
Put Washington’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/washington-dc" width="340" height="150" style="border:0" title="Live WBGT: Washington, DC" loading="lazy"></iframe>Paste it into any website. The badge updates itself and links back here. Add ?theme=light for light sites.