Houston, TX UV Index Today
What is the UV index in Houston right now?
2 Low
EPA describes low UV as needing no protection for most people.
Today's peak is 8.6 (Very High) at about 1pm local time.
When is UV strongest in Houston today?
UV in Houston peaks at 8.6 (Very High) around 1pm local time (GMT-5). It stays at 6 or above — the high band — for 4 hours, roughly 12pm to 4pm. UV is 3 or above for 7 hours.
Houston today, in numbers
- Latitude
- 29.8°N — 115 of 121 from the north
- Today's peak
- 8.6 (Very High) — 14 of 121 nationally
- Peak arrives
- 1pm local (GMT-5)
- At or above 6
- 4 hours, 12pm to 4pm
- At or above 3
- 7 hours, 10am to 5pm
The window from 12pm to 4pm is the practical answer for Houston 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 →
Gulf convection builds into the peak hour
What decides a Houston UV day in summer is usually not how high the sun gets but whether cloud has built before the sun gets there. Gulf moisture drives a daily cycle that runs like clockwork from June into September: mornings largely clear, cumulus fields thickening through the middle of the day, and much of the metro under cloud by mid-afternoon.
That collides with the clock. Houston lies far west inside the Central time zone, so solar noon falls near 1:21 p.m. on daylight time, more than twenty minutes later than the clock suggests, and close to the hour the convection is filling in. The theoretical peak and the daily cloud maximum arrive together. Whether a given afternoon reaches its ceiling can come down to where one cell happens to form and which way it drifts.
The ceiling itself is high. In late June the noon sun passes within about six degrees of straight overhead. At the December solstice it still reaches around 37 degrees, higher than Chicago’s noon sun manages on any day in December or January. The season that actually delivers that geometry is not summer. Drier continental air behind a fall or late-winter front leaves long clear stretches under a sun that stays higher than most of the country’s, and none of it is being softened by convection because the Gulf is not feeding any. October and March do the quiet damage here; July is loud and frequently interrupted.
Nearest metros we model
What does Houston’s UV index mean today?
2 is Low. EPA describes low UV as needing no protection for most people. Today Houston 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.
Modelled, not measured
The UV figures for Houston 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 Houston
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