BreatheCheck LIVE Get alerts

Tucson, AZ UV Index Today

Modelled for · GMT-7

What is the UV index in Tucson right now?

3.8 Moderate

EPA suggests shade around midday, a hat and sunglasses.

Today's peak is 9.1 (Very High) at about 12pm local time.

When is UV strongest in Tucson today?

UV in Tucson peaks at 9.1 (Very High) around 12pm local time (GMT-7). It stays at 6 or above — the high band — for 4 hours, roughly 11am to 3pm. UV is 3 or above for 7 hours.

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

Tucson today, in numbers

Latitude
32.2°N — 108 of 121 from the north
Today's peak
9.1 (Very High) — 6 of 121 nationally
Peak arrives
12pm local (GMT-7)
At or above 6
4 hours, 11am to 3pm
At or above 3
7 hours, 9am to 4pm

The window from 11am to 3pm is the practical answer for Tucson 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 →

Monsoon Cloud Arrives After The Peak

Arizona does not observe daylight saving time, and in Tucson that moves the whole shape of the day. Through the high-sun months, solar noon at this longitude lands around half past twelve on the clock. In a neighboring state that shifts its clocks, the same instant reads an hour later. The strongest stretch of the day here falls inside the lunch hour rather than after it.

Latitude does the rest. Tucson lies at 32.22°N, south of San Diego, Dallas and Phoenix, which keeps the noon sun high in every month of the year. About 2,400 feet of Sonoran Desert elevation adds a few percent more on top of that, pushing the same direction rather than against it.

For most of the year the sky adds no complication; the desert air is dry and the days run cloudless. The North American Monsoon is the exception, running mid-June into September with the strongest activity in July and August. Moisture drawn off the Gulf of California feeds convection, and the Santa Catalina Mountains along the city’s northern edge lift it into cumulonimbus by two or three in the afternoon. Tucson’s cloudiest weeks are therefore also its highest-sun weeks, and a monsoon day tends to run a clear morning at full strength before shutting down under a storm.

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.

Scottsdale, AZ 104 mi · 33.5°N peak 8.3 Phoenix, AZ 106 mi · 33.5°N peak 8.3 Albuquerque, NM 317 mi · 35.1°N peak 7.6

What does Tucson’s UV index mean today?

3.8 is Moderate. EPA suggests shade around midday, a hat and sunglasses. Today Tucson 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 Tucson 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 Tucson

What is the UV index in Tucson today?

3.8 right now (Moderate), peaking at 9.1 around 12pm local time. UV stays at 6 or above for 4 hours, from about 11am to 3pm. This is a modelled value, not a ground measurement.

When is UV strongest in Tucson today?

Around 12pm 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.

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

Updated