If you ever have to make a blind bet on that day's weather in Tucson, bet sunny, and you'll win more than 96% of the time. With 350+ days of sunshine a year, Tucson is one of the sunniest cities in the United States! That translates to fun events all year, sports and outdoor activities even in midwinter, and family-friendly weather that almost never gets in the way of things to do.
Apple Watch, its power adapter, and Apple Watch Magnetic Charging Cable follow applicable surface-temperature standards and limits. Even within these limits, sustained contact with warm surfaces for long periods of time might cause discomfort or injury.
I can't imagine any good way for a wristwatch to measure core temperature (as compared to peripheral temperature), or blood pressure (without an obtrusive and annoying sphygmomanometer), or respiratory rate. Heart rate and O2 are cake by comparison.