If you’re worried about sunburn this summer, a number of iPhone apps can keep you from frying with advice and reminders. Here is a look at three.

Sun Alert Lite (free, or 99 cents for a full-featured version), the easiest to use, has dials with icons to show skin type, your sunscreen’s SPF (sun protection factor) and weather conditions.

When the dials are set, the app tells you how much time to stay outside. An alarm beeps when time is up.

Sunscreen ($1.99) has three dials marked for ultraviolet index, SPF and Skin, showing numbers without explanation. To get your UVI, you go to the map tab, touch the search box, then the button that will appear on the upper left. The phone will find your location and set the UVI for you.

Sunblock ($1.99) automatically sets your UVI, according to your location, but you have to go into settings to find your skin type and to switch on “snow,” “grass/concrete” or “beach/ocean.” There’s an altimeter, which accounts for high exposure in the mountains. The app tells you how long you can stay in the sun, but there is no timer.