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.

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.