In an area that reaches extreme UV indexes I would find it useful to know for a for a given start time in the morning and the afternoon how much time I have before burning for the conditions on the day.
UV forecast graphs take some of the guesswork out of location and time, but I find that it hard to judge how much cloud cover is needed to drop from a high to a low index range. Sunscreen is great but it's not much fun to have to be covered in goop every day. Getting burnt when it's cloudy isn't much fun either. Knowing your exposure would limit the amount of cream.
UV forecast graphs take some of the guesswork out of location and time, but I find that it hard to judge how much cloud cover is needed to drop from a high to a low index range. Sunscreen is great but it's not much fun to have to be covered in goop every day. Getting burnt when it's cloudy isn't much fun either. Knowing your exposure would limit the amount of cream.