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Baltimore, MD UV Index Today

Modelled for · GMT-4

What is the UV index in Baltimore right now?

0.4 Low

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

Today's peak is 6.2 (High) at about 1pm local time.

When is UV strongest in Baltimore today?

UV in Baltimore peaks at 6.2 (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.

Baltimore today, in numbers

Latitude
39.3°N — 60 of 121 from the north
Today's peak
6.2 (High) — 78 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 Baltimore 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 →

Inside the bay-breeze zone, not inland of it

Baltimore and Washington sit about forty miles apart and get much the same sun, but only one of them is on the Chesapeake. Baltimore is built around the Patapsco, a tidal arm of the bay that carries estuary water into the middle of the city, with the open bay a short way to the east.

On summer afternoons the land warms faster than the estuary does, and the cooler air standing over the water pushes inland as a bay breeze. Cumulus builds along its leading edge, and a clear morning at the harbor can go to broken sky inside the hour the boundary arrives. Because that boundary keeps moving, it also splits the metro: the sky over Fort McHenry and the sky over the northwestern suburbs can behave differently through the same afternoon instead of tracking each other.

The timing is what gives it weight. A bay breeze normally gets going in the early afternoon, close to the strongest part of the day, so on the days it forms the cloud arrives at the hour that counts for most, and on the days it stalls the waterfront stays open to full sun. Forty miles inland, Washington sits past the usual reach of that boundary and has its afternoons decided by something else.

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.

Washington, DC 35 mi · 38.9°N peak 6.3 Philadelphia, PA 90 mi · 40.0°N peak 6 New York, NY 169 mi · 40.7°N peak 5.9

What does Baltimore’s UV index mean today?

0.4 is Low. EPA describes low UV as needing no protection for most people. Today Baltimore 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 Baltimore 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 Baltimore

What is the UV index in Baltimore today?

0.4 right now (Low), peaking at 6.2 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 Baltimore 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.

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

Updated