alt Hacker NewsWorth noting here for any readers new to UV guidelines that the above rule isn’t necessarily helpful for you. I’m currently traveling in an area that is 8:30am-4:30pm and live in an area that’s 10-6 pm in the summer and shifts throughout the year.
The actual rule is derived from your location’s safe UV index zones, which is found out by determining what local time the UV Index <= 2. Above 2, wear some amount of protection.
That's basically sun up to sun down, here.
It's been completely grey, overcast, and raining here all day and the UV index sat between 3 and 5.