[autokad]

it seems highly unlikely the mother, father, and dog all died of heat exhaustion at the same time, unless the dog died/passed out and they were carrying it. Even then, I would have suspected the mother/daughter taking cover and the dad going ahead.

[carabiner]

Incredibly rare. Huge numbers of people hike the PCT in the desert every year, and some years 1 or 2 people die of heat exhaustion. It's never big groups of people at the same time. Same with heat-related deaths at Grand Canyon, Death Valley etc.