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Charleston, SC UV Index Today

Modelled for · GMT-4

What is the UV index in Charleston right now?

0.5 Low

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

Today's peak is 7.4 (High) at about 1pm local time.

When is UV strongest in Charleston today?

UV in Charleston peaks at 7.4 (High) around 1pm local time (GMT-4). It stays at 6 or above — the high band — for 3 hours, roughly 12pm to 3pm. UV is 3 or above for 7 hours.

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

Charleston today, in numbers

Latitude
32.8°N — 102 of 121 from the north
Today's peak
7.4 (High) — 46 of 121 nationally
Peak arrives
1pm local (GMT-4)
At or above 6
3 hours, 12pm to 3pm
At or above 3
7 hours, 10am to 5pm

The window from 12pm to 3pm is the practical answer for Charleston 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 →

The Sea Breeze Arrives After the Peak

At 32.78 degrees north the June sun over Charleston Harbor climbs to about 81 degrees, close enough to straight overhead that midday shadows nearly disappear and the difference between one summer week and the next is decided almost entirely by cloud. What decides the cloud here is the water temperature difference across the coastline.

Land warms faster than the ocean through the morning. By early afternoon the cooler marine air is moving inland, and the boundary where it meets the warmer air ahead of it lifts that air and regularly fires thunderstorms. The boundary keeps pushing inland and often stalls some miles back from the water, which is why North Charleston can be under heavy rain while the peninsula between the Ashley and the Cooper, Folly Beach and Sullivan’s Island stay in sun.

For ultraviolet the consequence is a matter of timing rather than intensity. That build happens after the sun has already passed its highest point, so on a typical July or August day the clearest hours are the ones on either side of solar noon and the storm that ends the afternoon arrives when the index is well down from its peak. A day that people remember as stormy can still have delivered its full ultraviolet load before the first cloud went up.

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.

Columbia, SC 106 mi · 34.0°N peak 7.6 Charlotte, NC 177 mi · 35.2°N peak 7.4 Jacksonville, FL 198 mi · 30.3°N peak 7.9

What does Charleston’s UV index mean today?

0.5 is Low. EPA describes low UV as needing no protection for most people. Today Charleston 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 Charleston 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 Charleston

What is the UV index in Charleston today?

0.5 right now (Low), peaking at 7.4 around 1pm local time. UV stays at 6 or above for 3 hours, from about 12pm to 3pm. This is a modelled value, not a ground measurement.

When is UV strongest in Charleston 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.

Air quality across the USCharleston has no air-quality page — we publish one where searches for a metro clear a floor UV across the USWhere Charleston sits against every metro we track

Updated