Most people think that when the sun is behind the clouds that they are safe from the suns harmful UVA and UVB rays and don't need to worry about things like rash guards. You only get sun damage when its sunny, right? This has to be one of the biggest misconceptions about sun protection as on cloudy days, 90% of the UVA and UVB rays can actually pass through the clouds.
Conclusion to this is that you always need to be thinking about sun protection on both cloudy and sunny days. Things like wearing UPF protective rash guards when outdoors, putting sunscreen on exposed skin and always wearing a hat and sunnies will help protect your skin.
There is a large percentage of people who get sunburnt whilst just doing everyday chores such as gardening, shopping, cleaning the car, etc so sun protection is something to always be aware of. One of the easiest ways is to wear a sun protective top such as a rash guard and of course sunscreen, sunnies and a hat.