BreatheCheck LIVE Get alerts

Fresno, CA UV Index Today

Modelled for · GMT-7

What is the UV index in Fresno right now?

4.8 Moderate

EPA suggests shade around midday, a hat and sunglasses.

Today's peak is 7.5 (Very High) at about 1pm local time.

When is UV strongest in Fresno today?

UV in Fresno peaks at 7.5 (Very High) around 1pm local time (GMT-7). It stays at 6 or above — the high band — for 3 hours, roughly 12pm to 3pm. UV is 3 or above for 6 hours.

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

Fresno today, in numbers

Latitude
36.7°N — 79 of 121 from the north
Today's peak
7.5 (Very High) — 42 of 121 nationally
Peak arrives
1pm local (GMT-7)
At or above 6
3 hours, 12pm to 3pm
At or above 3
6 hours, 10am to 4pm

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

December sunlight, and the fog that removes it

Fresno stands mid-valley on the San Joaquin floor, near the middle of the tule fog belt rather than at either end of it. Under a settled winter fog the valley can go several days without breaking, and midday passes with the index near the bottom of the scale. Nothing local pushes back: the ground is flat, the elevation is a few hundred feet, and the Sierra front is far enough east that its snow reflects for the mountains and not for the city.

That floor is also thinning. UC Berkeley researchers, working from more than three decades of satellite records, measured a 46 percent drop in the number of fog days since 1981, and later work tied the decline to falling particulate pollution, which supplies the nuclei fog droplets condense on.

The other half of the year is unusual for its steadiness rather than its height. Effectively all of Fresno’s rain, around eleven inches, falls between November and April, so from May into September the observed index follows the clear-sky curve for long consecutive runs instead of crossing above and below it the way a summer-convection climate does. The peak value is ordinary for the latitude. The number of days that reach it is not.

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.

Bakersfield, CA 104 mi · 35.4°N peak 8.3 Stockton, CA 118 mi · 38.0°N peak 6.7 San Jose, CA 123 mi · 37.3°N peak 7.2

What does Fresno’s UV index mean today?

4.8 is Moderate. EPA suggests shade around midday, a hat and sunglasses. Today Fresno also reaches Very 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 Fresno 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 Fresno

What is the UV index in Fresno today?

4.8 right now (Moderate), peaking at 7.5 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 Fresno 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.

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

Updated