# Phoenix, AZ UV Index Today — hourly UV forecast

> Source: https://breathecheck.com/uv-index/us/arizona/phoenix/
> UV index in Phoenix, AZ right now, today's peak and the hour it arrives, on the EPA scale. Modelled data, labelled as modelled.

# Phoenix, AZ UV Index Today

Modelled for 14 Sep 2026, 22:00 UTC · GMT-7

## What is the UV index in Phoenix right now?

4.2 Moderate

EPA suggests shade around midday, a hat and sunglasses.

Today's peak is 8.3 ( Very High ) at about 12pm local time.

## When is UV strongest in Phoenix today?

UV in Phoenix peaks at 8.3 (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.

## Phoenix today, in numbers

- **Latitude**: 33.5°N — 101 of 121 from the north

- **Today's peak**: 8.3 (Very High) — 19 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 Phoenix 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 →

## Skipping daylight saving fixes the peak hour

Arizona last observed daylight saving time in 1967. Everywhere on the mainland except here, the clock time of the daily maximum jumps an hour in March and back in November, and people relearn it twice a year. In Phoenix it does not move. The city sits well west of the 105th meridian that anchors Mountain time, so the sun crosses closest to overhead roughly 28 minutes after clock noon, in January as much as in July, drifting only with the seasonal equation of time.

Cloud is a short season rather than a year-round variable. The National Weather Service defines the Arizona monsoon as June 15 through September 30, and that window holds nearly all of the reliable interruption to clear sky. Its storms build in the afternoon and evening, generally after the daily maximum has already passed. Outside it, the Sonoran Desert delivers long unbroken runs of cloudless days.

Two smaller factors sit underneath. The valley floor is about 1,086 feet, enough to matter slightly, and considerably more on South Mountain or in the McDowells. Reflectance is the underrated one: WHO puts dry sand near 15 percent against under 10 for grass, so bare desert ground and pale hardscape return more from below than a lawn does, and this metro is built mostly of the former. That ground does not change with the season either. It reflects the same in February as it does in August.

## 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.

## What does Phoenix’s UV index mean today?

4.2 is Moderate. EPA suggests shade around midday, a hat and sunglasses. Today Phoenix 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 Phoenix 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 Phoenix

**What is the UV index in Phoenix today?**

4.2 right now (Moderate), peaking at 8.3 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 Phoenix 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.

## Related

On this page

Air quality alerts

We alert on AQI, not UV — UV is predictable from the calendar, air quality is not.

Updated 14 Sep 2026, 22:00 UTC