Running the Shiprock Marathon in N.M. Was out there for over 4 hours - clear skies, 4900' elevation,
80+ degrees wearing a sleeveless shirt. Arms, shoulders, face neck/upper back and legs were all fried.
Nightmare. I looked like a lobster for a week and then like a zombie for 2 more weeks. Never again. Always wore a long sleeved shirt with a high neck after that.