Fort Collins, CO UV Index Today
What is the UV index in Fort Collins right now?
2.9 Moderate
EPA suggests shade around midday, a hat and sunglasses.
Today's peak is 7.3 (High) at about 1pm local time.
When is UV strongest in Fort Collins today?
UV in Fort Collins peaks at 7.3 (High) around 1pm local time (GMT-6). It stays at 6 or above — the high band — for 3 hours, roughly 12pm to 3pm. UV is 3 or above for 6 hours.
Fort Collins today, in numbers
- Latitude
- 40.6°N — 49 of 121 from the north
- Today's peak
- 7.3 (High) — 48 of 121 nationally
- Peak arrives
- 1pm local (GMT-6)
- 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 Fort Collins 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 →
The same sun as Pittsburgh, a mile less atmosphere
Pittsburgh and Fort Collins get the same sun. At 40.6 degrees north the two are a fifth of a degree apart, and the sun’s path overhead on any given date is essentially identical. What differs is what the light passes through on the way down. At roughly 5,000 feet, about 1,525 meters, the WHO’s rule of thumb of 10 percent more UV per 1,000 meters puts the ceiling here on the order of 15 percent above a sea-level city on the same parallel, before cloud enters the comparison at all.
Longitude produces a smaller oddity. At 105.08 degrees west the city lands almost exactly on the 105th meridian that defines Mountain Time, so in standard time the clock and the sun agree to within about a minute, and under daylight saving the sun crosses within a minute of 1 p.m.
The rest is a daily cycle rather than a season. Fort Collins stands where the Cache la Poudre leaves its canyon at the edge of the Front Range, and through the warm months the cloud that matters here is built over the mountains and carried east onto the plains during the afternoon. It arrives from the western side of town, on something close to a schedule, and it arrives with the sun still high. Mornings are the dependable half of a summer day; the second half depends on what the range did with the heat.
Nearest metros we model
What does Fort Collins’s UV index mean today?
2.9 is Moderate. EPA suggests shade around midday, a hat and sunglasses. Today Fort Collins 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 Fort Collins 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 Fort Collins
What is the UV index in Fort Collins today?
When is UV strongest in Fort Collins today?
Is this measured or modelled?
Related
Updated