Boise, ID UV Index Today
What is the UV index in Boise right now?
3.6 Moderate
EPA suggests shade around midday, a hat and sunglasses.
Today's peak is 5.9 (High) at about 1pm local time.
When is UV strongest in Boise today?
UV in Boise peaks at 5.9 (High) around 1pm local time (GMT-6). It does not reach the high band at any hour today. UV is 3 or above for 6 hours.
Boise today, in numbers
- Latitude
- 43.6°N — 19 of 121 from the north
- Today's peak
- 5.9 (High) — 85 of 121 nationally
- Peak arrives
- 1pm local (GMT-6)
- At or above 6
- not today
- At or above 3
- 6 hours, 11am to 5pm
Boise never reaches the high band today; the midday hours still warrant a hat. 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 →
Clock noon and solar noon disagree by 45 minutes
Boise sits near the far western edge of the Mountain time zone. At 116.2 degrees west it lies more than eleven degrees west of the 105th meridian the zone is built around, which puts mean solar noon roughly 45 minutes after noon on the clock — under daylight saving, the sun reaches its highest point close to 1:45 in the afternoon. The exact crossing wanders up to about a quarter hour either side of that across the year, but the direction never reverses. The UV peak here lands later on the clock than in most of the country, and later than the phrase “midday sun” implies.
Summer holds that peak steady. Boise’s climate is classified cool semi-arid, with roughly 12 inches of precipitation a year and summers drier still, so through July and into August there is little cloud to knock a reading down from one day to the next.
Winter runs the other way. From November into February the Treasure Valley collects cold air under the higher ground around it, and the inversion that follows can hold fog and low stratus over the city for days at a time. Above the deck, on ground a few hundred feet up the foothills, the air is often clear. The valley floor and the slope behind it can spend a week under different skies.
Nearest metros we model
What does Boise’s UV index mean today?
3.6 is Moderate. EPA suggests shade around midday, a hat and sunglasses. Today Boise 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.
Modelled, not measured
The UV figures for Boise 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 Boise
What is the UV index in Boise today?
When is UV strongest in Boise today?
Is this measured or modelled?
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