Trying to figure out why she was wearing those long sleeves in 90 degree heat! Being from AK I’d presume she’d find it unbearable.
She was wicked sunburned!
Having done the same thing, I can take a guess at the answer: sunscreen. The lightweight cotton will not roast her if she chose the right shirt, and cotton is a whole lot more durable, comfortable, and photogenic than many sunscreen formulations with a similar SPF. As much as I love Sarah, I'd guess that she falls short in the area of tanning, and constantly reapplying sunscreen anywhere that it might have rubbed off would distract and detract from her tour (although I'd guess there are thousands of FReepers who would volunteer to take over that responsibility for the duration of her tour) as would missing a spot and getting a severe sunburn on a bare patch. I could be wrong, but that makes sense to me.