The US Cities Where You Burn Fastest: 2026 UV Rankings

We computed the clear-sky summer peak UV index for the 500 largest cities in the United States. In 168 of them, it reaches "extreme" (11+) — a level where unprotected fair skin can begin to burn in roughly 8 minutes. The fastest-burning city is Honolulu, HI, at a computed midsummer peak of UV 12.7. Even in the slowest-burning city on the list — Anchorage, AK — fair skin burns in about 18 minutes of clear midday sun.

The table below shows the top 50. The full 500-city dataset is available as a CSV download, free to use with attribution.

Key Findings

• Honolulu is #1 — and it isn't close to leaving. At latitude 21°N, the summer sun passes almost directly overhead, producing a computed clear-sky peak of UV 12.7. It is also the only city of the 500 whose winter peak stays above UV 5 — sunscreen weather every month of the year.
• Altitude rivals latitude. Flagstaff, AZ (~6,800 ft) and Santa Fe, NM (~6,800 ft) rank #2 and #3 nationally — ahead of nearly all of Florida despite sitting about 600 miles further north. Thin high-altitude air filters less UV; Denver's computed peak runs about 15% higher than sea-level cities at the same latitude, such as Kansas City.
• Extreme UV is not a desert niche. 168 of the 500 cities — roughly one in three — reach the WHO's "extreme" category (11+) at their summer clear-sky peak, and 308 reach at least "very high" (10+).
• South Florida owns the top 50. Florida places 30 of the 50 fastest-burning cities, Texas 13. The border-region cluster — El Paso (#4), Las Cruces (#5), Laredo, Brownsville, McAllen — combines low latitude with elevation or relentless clear skies.
• There is no "safe" major city. Only Anchorage, AK takes longer than 14 minutes to burn (about 18). Seattle — famously cloudy — still reaches a clear-sky summer peak of UV 7.7, enough to burn fair skin in about 13 minutes.
• Winter doesn't mean off-season. 82 of the 500 cities — nearly all in Florida, Texas, and the Gulf Coast — still reach moderate UV (3+) at their clear-sky winter peak, the threshold where the WHO recommends sun protection.

Top 50: Minutes to Burn at Clear-Sky Summer Peak UV

Estimated time for unprotected fair (Type II) skin to begin burning at each city's computed clear-sky summer peak UV index. Ties are ordered by population. The full ranking of all 500 cities (CSV) includes population, coordinates, elevation, and winter values.

Download the full 500-city dataset (CSV, ~30 KB)

The Cities Where Sunscreen Is a Year-Round Habit

These 37 cities reach a computed clear-sky winter peak of UV 4 or higher — comparable to a late-spring afternoon in the northern US. In total, 82 of the 500 cities stay at moderate (3+) even in midwinter.

Methodology

Cities. The 500 most populous incorporated places in the United States, from the US Census Bureau's Vintage 2025 subcounty population estimates, with centroid coordinates from the 2025 Census Gazetteer. The smallest city on the list has about 77,000 residents.

UV computation. For each city we computed the clear-sky UV index at solar noon on the summer and winter solstices using the empirical model of Allaart et al. (2004) — the parametrisation behind the KNMI/TEMIS UV forecasts — driven by each city's solar zenith angle and climatological total ozone for its latitude. We then applied the WHO's elevation correction of roughly 10% more UV per 1,000 m of altitude, using each city's elevation from terrain data. Elevation is why Flagstaff and Santa Fe outrank most of Florida.

Burn time. Estimated with the standard Fitzpatrick skin phototype approximation used by our live UV tool: for fair Type II skin, roughly 100 minutes to burn at UV 1, divided by the UV index. At UV 12 that yields about 8 minutes.

What these numbers are — and aren't. These are computed clear-sky peaks: the UV your city reaches on a cloud-free solstice day at solar noon. Clouds reduce UV on any given day (an unbroken layer typically cuts it 50–60%), so cloudier cities will see fewer days at their peak — but the peak is what matters when you plan for the worst case, and thin clouds pass most UV through. Live, cloud-adjusted values for any city are on its city page. Burn times are population-level estimates; individual response varies with medications, skin conditions, and prior exposure. Darker skin types burn more slowly (Type IV roughly triples these times) but UV damage accumulates for all skin types. Cross-checked against our tracked cities' observed UV ranges, the computed peaks agree within about one UV point. Full details on our data pipeline are on the Data & Methodology page. This analysis is informational, not medical advice.