Have your time in the sun, and not a minute longer

I would bet that more than once over the last several weeks you have forgotten to put sunscreen on before you went outside, even though we all know the dangers of getting too much sun. As in so many situations, your smartphone can come to the rescue, with sunshine prediction and advice apps.

Wolfram Sun Exposure

$1 on iOS

The most comprehensive one I’ve found is Wolfram Sun Exposure Reference App, $1 on iOS. It calculates a lot of detailed information in real time about your sunburn risks.

To start, you either let the app work out where you are or type a location into the “Time to Sunburn” section. Then you enter your skin type and whether you are wearing any sunscreen in the relevant boxes. The app calculates the UV index at that moment for your location and tells you how quickly your skin will burn if exposed to the sun. You use this information to work out how long it is safe to be out in the heat of the day.


The app even tells you how you should dress to protect yourself from the sun and provides a suggestion for sunscreen strength.

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The “UV forecast” section of the app shows a more detailed prediction of coming UV levels and has a map that is a little like the rain charts you see in TV weather forecasts, this one showing damaging solar ray levels instead.

It also provides detailed calculations of the sun’s position in real time and has a straightforward weather forecast.

Wolfram is great for planning sensible beach days. Its no-nonsense displays are informative and fairly easy to read. But some may find that it offers too much information — more than many of us will need, and potentially confusing.

There is also no version for other mobile platforms. On Android, Nook, and Kindle Fire devices, however, you can download the full search app Wolfram Alpha for $3 and type in “what’s the UV index here now?” to get some of the same detailed UV predictions.


$2 on iOS


On iOS, iTanSmart offers a single screen that contains all the information you need. At the top, you select whether you want to avoid sunburn or achieve some safe tanning. You also enter your skin type and the protection factor of the sunscreen you have applied. The app then looks up the UV levels for your location and works out safe exposure times.

When you tap the Start button as you go outside, it starts a timer in a colorful alert bar to tell you how much time you have left to spend in the sun and when more sunscreen is needed. When it is time to seek shade or reapply lotion, it will alert you visually and with sounds.

Kit Eaton writes on technology for The New York Times.