UV Hour

How long can you tan in UV 10?

10 UV Index
Very high UV

At UV 10, skin type II reaches the first redness in about 17 min with no sunscreen, and about 8 h 20 with SPF 30. Type I has 13 min; type VI has 40 min. UV 10 is in the very high band (8–10).

Northern Australia, southern Africa in December and January, the Andes and the Himalaya in summer, and the equatorial belt year-round.

Today in Columbus

UV 0 right now (low) · peak UV 8.6 at 14:00 · skin type II window 11:07–11:35 and 16:36–17:49

8.6 peak today
Very high UV
  • 14:00 Peak UV hour
  • 19 min Time to redness at peak, type II
  • 11:07–11:35 First of 2 windows
  • 11:20–17:13 Protection recommended (UV 3+, WHO)
0 2 4 6 8 10 06:00 09:00 12:00 15:00 18:00 21:00 8.6 our 40-min cut-off — UV 4.2 06:13
Your window Under 40 min to redness UV index
Today's window in Columbus, by skin type. Times are local.
Skin typeWindowTime to redness at peak UV 8.6
I17:03–17:4916 min
II11:07–11:35, 16:36–17:4919 min
III11:07–11:45, 16:13–17:4923 min
IV11:07–12:20, 15:21–17:4931 min
V11:07–13:34, 14:14–17:4939 min
VI11:07–17:4947 min

Burn times at UV 10, by skin type and SPF

Minutes of unprotected sun before the first redness, at UV 10. Below 20 minutes is shown in red.
Skin type No SPFSPF 15SPF 30SPF 50
I — Always burns, never tans. 13 min 3 h 20 6 h 40 11 h 07
II — Burns easily, tans minimally. 17 min 4 h 10 8 h 20 13 h 53
III — Burns moderately, tans gradually. 20 min 5 h 10 h 16 h 40
IV — Burns rarely, tans easily. 27 min 6 h 40 13 h 20 22 h 13
V — Burns very rarely, tans very easily. 33 min 8 h 20 16 h 40 over 24 h
VI — Almost never burns, always tans. 40 min 10 h 20 h over 24 h

Every figure is 0.667 × MED ÷ UV, the standard erythemal formula. The MED values are the published Fitzpatrick doses: 200 to 600 J/m² from type I to type VI. See the full method.

What UV 10 actually means

UV 10 is the top of the very high band. Fair skin reaches the first redness in about 13 minutes — shorter than the time it takes to apply sunscreen, swim, and dry off. At this level the useful question is no longer how long you can stay out, but whether there is any hour of the day when you can.

What to do: For type I and II there is usually no unprotected window at all. Plan the day around dawn and dusk, or plan it indoors.

Official guidance for the very high band (8–10): Extra protection. Avoid the sun between 11:00 and 15:00.

UV 10 with sunscreen

Your skin type at UV 10

Where the sun is strongest right now

Nowhere we track peaks at exactly UV 10 on its current forecast day. Here is where the sun is strongest instead.

UV 10 — the questions people actually ask

How long can you stay in UV 10 without burning?

At UV 10, unprotected skin reaches the first visible redness after about 13 min for Fitzpatrick type I, 17 min for type II, 20 min for type III and 40 min for type VI. Those figures assume a clear sky, sea level, and no reflective surface.

Is UV 10 strong enough to tan?

Yes. UV 10 is in the very high band, well above the UV 2 threshold where skin starts producing melanin. The constraint at UV 10 is not whether you can tan, it is how long before you cross into a burn — 17 min for type II.

How long can you stay in UV 10 with SPF 30?

SPF 30 multiplies the unprotected time by 30 in laboratory conditions, so type II goes from about 17 min to about 8 h 20 at UV 10. Real-world protection is usually lower because most people apply about a quarter of the tested amount, and because sunscreen comes off with water and towels.

Does cloud cover change how long you can tan at UV 10?

Less than people expect. A completely overcast sky cuts UV 10 to roughly UV 2.5; a half-covered sky cuts it by about 7%. That is why sunburn on a grey day is common — the heat drops far more than the UV does.

What is the safe UV limit for my skin type?

UV Hour uses one rule: stay below the UV level that leaves at least 40 minutes before the first redness. That gives UV 3.3 for type I, UV 4.2 for type II, UV 5 for type III and UV 10 for type VI. At UV 10, types VI still do.