Yes — “Very high” is the literal category name. WHO’s Table 1 defines the Very high band as 8 to 10, and 8 is its lowest value.

WHO category: Very high (8 to 10)

How fast do you burn in UV 8?

At UV index 8, the erythemal-dose model computes a first-perceptible-reddening reference dose after roughly 17 minutes of continuous unprotected exposure for Fitzpatrick skin type I, and roughly 83 minutes for type VI. The full type I–VI table is below, with the arithmetic and the sources.

Computed from a dose rate of 7.2 standard erythema doses per hour at UV index 8. Reference values, not measurements of any individual.
Fitzpatrick skin type	Reference dose to first erythema (SED)	Minutes to that dose at UV 8	0.6 × that figure (min)
Type Ialways burns, never tans	2	17	10
Type IIusually burns, tans minimally	2.5	21	13
Type IIIsometimes mild burn, tans uniformly	3.5	29	18
Type IVburns minimally, always tans well	4.5	38	23
Type Vvery rarely burns, tans easily	6	50	30
Type VIdeeply pigmented, never burns	10	83	50

The fourth column is a fixed 0.6 multiple of the third — an arithmetic margin for the roughly ±30–50% spread in published reference doses within one phototype. It is what the app reports.

“Reporting burn times is not recommended.”

— WHO, WMO, UNEP and ICNIRP, Global Solar UV Index: A Practical Guide, WHO/SDE/OEH/02.2 (2002)

The guide gives its reasoning directly: “people tend to interpret burn times to mean that there is a safe level of unprotected sun exposure”, and relating index values to a time to burn therefore “sends out the wrong message”.

Why we publish the figure anyway →

This page answers the UV 8 question. The app answers yours.

Real days do not sit at 8 — the index climbs to a peak and falls again. Safe Sun Window takes your skin type and the index where you actually are, and runs this same calculation on those inputs. Free, no account, no ads. Return visits are counted with a random first-party id that goes to no one else. If you turn on location, your device rounds your position to about 10 km before it reaches our weather provider for the UV reading, with no id attached.

Open Safe Sun Window →

What UV 8 means

Eight opens WHO’s Very high band (8 to 10) and is the point at which the US EPA’s published guidance changes wording, from “Protection needed” to “Extra protection needed”. It is the only place on the scale where that particular threshold sits.

At 8 the erythemal dose rate is 8/3 that of UV 3, so every modelled threshold below is 37.5% of its UV 3 value — the same skin, the same exposure, reaching the same reference dose in a little over a third of the time.

Where and when UV 8 actually occurs

Eight needs a near-overhead sun, a thin atmosphere, or both at once. Readings of 8 typically come from:

Peak-summer clear-sky midday at mid-latitudes, and more readily in the southern hemisphere: Earth is at perihelion in early January, so southern summers receive a few percent more solar irradiance than northern ones at the same solar elevation.
Midday for most of the year in the subtropics.
Inside the four-hour solar-noon window in tropical latitudes, even outside peak season.
Mid-latitude summer above roughly 2000 metres, where WHO’s 10–12%-per-1000-metres altitude effect lifts a sea-level 7 into the Very high band.

A reading of 8 almost always belongs to the middle of the day. Outside the tropics, WHO notes, the highest levels occur when the sun is at its maximum elevation, around solar noon in the summer months — so a summer day that touches 8 will typically read 4 or 5 a few hours either side.

The six factors WHO lists as setting the index, with its own figures →

What the published guidance says at UV 8

Eight is where the US EPA’s published text changes. For 8 and above it publishes: “Extra protection needed. Be careful outside, especially during late morning through mid-afternoon. If your shadow is shorter than you, seek shade and wear protective clothing, a wide-brimmed hat, and sunglasses, and generously apply a minimum of SPF-15, broad-spectrum sunscreen on exposed skin.”

The EPA is not alone in singling out 8. The WHO guide names the same number independently: “Above the threshold value of 3, protection is necessary, and this message should be reinforced at UVI values of 8 and above.” Two separately published schemes, one shared inflection point. What WHO changes at 8 is the emphasis rather than the measures — the recommended set is the same from 3 upward — along with the colour code used in public reporting, where Table 4 assigns Red (PMS 032) to the Very high band.

The published scheme is binary, not graded: the same measures apply from UV 3 upward, and what changes with the index is the rate at which erythemal dose accumulates. Why the scheme is not graded →

Check the arithmetic

At UV 8, an hour of continuous exposure delivers 8 × 0.9 = 7.2 standard erythema doses. Fitzpatrick type II’s reference dose is 2.5 SED, so 2.5 ÷ 7.2 × 60 = 21 minutes. Every row in the table above is that division with a different reference dose.

The 0.9 factor is exact, and follows from the definition of the index; the reference doses are not. Where the 0.9 comes from, and what the reference doses are →

Questions

How fast do you burn in UV 8?: At UV index 8 the model computes a first-erythema reference dose in about 17 minutes of continuous unprotected exposure for Fitzpatrick type I skin and about 83 minutes for type VI. These are computed model outputs for a reference dose, not durations of demonstrated safety.
Is UV 8 very high?: Yes — “Very high” is the literal category name. WHO’s Table 1 defines the Very high band as 8 to 10, and 8 is its lowest value.

Other UV levels

All levels, the full method, and why burn times are contested →

Sources for the figures above

World Health Organization, World Meteorological Organization, United Nations Environment Programme and International Commission on Non-Ionizing Radiation Protection. “Global Solar UV Index: A Practical Guide.” WHO/SDE/OEH/02.2, 2002.
ISO 17166:1999 / CIE S 007/E-1998. Erythema reference action spectrum and standard erythema dose.
United States Environmental Protection Agency. “UV Index Scale.” epa.gov, last updated 15 June 2026; verified 3 August 2026.
Fitzpatrick TB. “The validity and practicality of sun-reactive skin types I through VI.” Archives of Dermatology, 1988;124(6):869–871.
Minimal-erythema-dose values per Fitzpatrick phototype — working reference values, range-checked against ISO 17166:1999; the six-value progression itself is not traced to a named primary document.

Full annotated source list, with what each one is used for →