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Seattle, WA UV Index Today

Modelled for · GMT-7

What is the UV index in Seattle right now?

2.7 Moderate

EPA suggests shade around midday, a hat and sunglasses.

Today's peak is 3.3 (Moderate) at about 1pm local time.

When is UV strongest in Seattle today?

UV in Seattle peaks at 3.3 (Moderate) around 1pm local time (GMT-7). It does not reach the high band at any hour today. UV is 3 or above for 2 hours.

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

Seattle today, in numbers

Latitude
47.6°N — 4 of 121 from the north
Today's peak
3.3 (Moderate) — 114 of 121 nationally
Peak arrives
1pm local (GMT-7)
At or above 6
not today
At or above 3
2 hours, 1pm to 3pm

Seattle never reaches the high band today; the midday hours still warrant a hat. 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 →

Cloud sets the ceiling for eight months

From October into May, what limits a Seattle UV day is usually the deck overhead rather than the geometry of the sun. NOAA’s Comparative Climatic Data records 226 days a year here on which cloud covers more than three-quarters of the sky. No other metro above a million people in that dataset posts a higher count, with Portland at 222.

The geometry is unhelpful too. At 47.6°N the noon sun climbs to only about 19 degrees at the December solstice, a little over half the elevation Phoenix gets on the same date. A low sun means a longer slant path through the atmosphere before anything reaches Puget Sound.

Summer changes the shape without changing what governs it. July is the driest and clearest month of the Seattle year, which produces a narrow run of genuinely high readings after eight months in which the index rarely left the low numbers. The solstice brings just under 16 hours of daylight, but the sun only reaches about 66 degrees even at its highest, so the long day is mostly low sun stretched across a very early morning and a very late evening. The hours that carry real strength are a smaller fraction of a Seattle June day than the daylight total implies.

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.

Portland, OR 145 mi · 45.5°N peak 3.8 Spokane, WA 228 mi · 47.7°N peak 2.8 Eugene, OR 249 mi · 44.0°N peak 5.3

What does Seattle’s UV index mean today?

2.7 is Moderate. EPA suggests shade around midday, a hat and sunglasses. Today Seattle also reaches Moderate at its peak .

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 Seattle 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 Seattle

What is the UV index in Seattle today?

2.7 right now (Moderate), peaking at 3.3 around 1pm local time. It does not reach the high band today. This is a modelled value, not a ground measurement.

When is UV strongest in Seattle today?

Around 1pm local time (GMT-7), 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.

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

Updated