In Montana, we spend the majority of the year hiding beneath thick layers of clothing. So when the temperature suddenly skyrockets — as it did earlier this week — it’s easy to forget that skin, when exposed to sunlight, can burn.

I realized this the hard way when I was outside Monday afternoon enjoying the day’s record-breaking heat. Blindingly pale in my shorts and tank top, I spent approximately 20 minutes hanging out in direct sunlight before I noticed a burning sensation on my chest and shoulders. By then, of course, it was too late. I was burned.

I suspect that many of my neighbors have had similar experiences, as I have seen a lot of red arms and faces over the past few days.

So, I figure now is as good a time as any to remind everyone of the benefits of SPF. Applying sunscreen might seem like an annoying extra step when you’re on your way out the door, but it can help prevent a lot of discomfort — and possibly even deadly skin cancer — in the future.

Most experts recommend wearing sunscreen with an SPF — Sun Protection Factor — between 15 and 50. Contrary to popular belief, the numerical value of SPF does not refer to the number of minutes the sunscreen will protect your skin from the sun. It is actually a rough estimation of how long it will take for a person’s skin to turn red based on that person’s individual tolerance for burn-causing ultraviolet (UV) rays.

For example, a person wearing SPF 15 theoretically can be exposed to direct sun 15 times longer than they could if they were not wearing any sunscreen at all. So, if you usually burn after 10 minutes, you would burn after 150 minutes with SPF 15.

But, even if you lather up with SPF 50, it is recommended that you reapply your sunscreen every two hours, as it tends to wash or rub off.

Brooke is a 2010 graduate of The University of Montana, where she ran track and cross country for the Grizzlies. She is currently working as a writer and editor in Missoula.