Inti Raymi sits at 3,400 metres. Snowbombing is on a glacier. Songkran is peak tropical heat. The most beautiful festivals often ask the most of your body.
The festivals with the best stories tend to be the ones at the edges of what is comfortable. That is the appeal, but it comes with a body tax you should plan for.
Altitude
Cusco for Inti Raymi sits at 3,400 metres. Mexico City for Dia de Muertos is over 2,200. Altitude sickness is real and it does not care how fit you are. Arrive two to three days early, hydrate hard, and consider medication from a travel clinic.
Cold and UV together
The cruelest combination is high-altitude snow: freezing air and brutal reflected UV at the same time, at Snowbombing and Inti Raymi alike. You can get sunburn and hypothermia on the same afternoon. Glacier-grade sunglasses and high SPF are not optional up there.
Tropical heat and humidity
Songkran, Rio Carnival, Sauti za Busara. The danger here is heat exhaustion and dehydration, accelerated by hours of dancing. Electrolytes, shade breaks and reef-safe sunscreen keep the trip from ending in a medical tent.
Acclimatise on purpose. The festival is not the place to find out how your body handles 3,400 metres.
Every profile includes a microclimate note and a recovery destination for exactly this reason. Build a soft day in after the intensity.