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Washington, DC UV Index Today

Modelled for · GMT-4

What is the UV index in Washington right now?

0.4 Low

EPA describes low UV as needing no protection for most people.

Today's peak is 6.3 (High) at about 1pm local time.

When is UV strongest in Washington today?

UV in Washington peaks at 6.3 (High) around 1pm local time (GMT-4). It stays at 6 or above — the high band — for 1 hour, roughly 1pm to 2pm. UV is 3 or above for 5 hours.

Local time, midnight to midnight. Bar colour is the EPA UV band, never restyled.

Washington today, in numbers

Latitude
38.9°N — 65 of 121 from the north
Today's peak
6.3 (High) — 74 of 121 nationally
Peak arrives
1pm local (GMT-4)
At or above 6
1 hour, 1pm to 2pm
At or above 3
5 hours, 11am to 4pm

The window from 1pm to 2pm is the practical answer for Washington today. Nationally today the spread runs 11.4 in Hilo (20°N) to 1.3 in Fargo (47°N). Why latitude and the clock decide this →

What sea level at 39 degrees north costs

Around the December solstice the midday sun over Washington climbs only about 28 degrees above the horizon. Six months later it reaches about 74. That swing is what latitude does here, and nothing in the local ground softens either end of it.

At 38.9°N the city sits north of San Francisco, Sacramento and St. Louis, and roughly level with Kansas City, which puts a ceiling on the summer peak that no Texas or Southwest metro has. The more specific limit is elevation. Most of the District lies within a few tens of feet of sea level, at the confluence of the Potomac and Anacostia where the Piedmont steps down to the Coastal Plain, and Fort Reno, the highest natural ground in the city, reaches 409 feet.

Denver shows what that costs. It lies farther north still, at 39.7°N, and stands about a mile above sea level. EPA lists altitude among the factors that raise ultraviolet at the surface, on the grounds that there is less atmosphere overhead to absorb it. Washington has no altitude to collect, and 409 feet does not enter into the arithmetic.

Nearest metros we model

UV changes with latitude, not with a city boundary, so a neighbour a hundred miles north reads differently for a reason.

Baltimore, MD 35 mi · 39.3°N peak 6.2 Philadelphia, PA 124 mi · 40.0°N peak 6 Virginia Beach, VA 153 mi · 36.9°N peak 6.6

What does Washington’s UV index mean today?

0.4 is Low. EPA describes low UV as needing no protection for most people. Today Washington also reaches High at its peak — a different band from the one it is in right now, which is why the hour matters as much as the day.

The scale is open-ended: 11 is where the named bands stop, not the maximum. All five bands, with the EPA guidance for each →

Modelled, not measured

The UV figures for Washington are computed by the Copernicus atmosphere model, not read off an instrument here — unlike the AQI on our air-quality pages, which comes from a regulatory monitor. Cloud is where a UV model is weakest. What that means in practice →

Questions about UV in Washington

What is the UV index in Washington today?

0.4 right now (Low), peaking at 6.3 around 1pm local time. UV stays at 6 or above for 1 hour, from about 1pm to 2pm. This is a modelled value, not a ground measurement.

When is UV strongest in Washington today?

Around 1pm local time (GMT-4), not at noon — solar noon drifts across a timezone and daylight saving moves it later on the clock.

Is this measured or modelled?

Modelled. The figures come from the Copernicus atmosphere model via Open-Meteo, unlike the AQI on our air-quality pages, which is read from an EPA regulatory monitor. Cloud cover is where a UV model is weakest.

Washington air qualityThe AQI, from a regulatory monitor rather than a model UV across the USWhere Washington sits against every metro we track

Updated