The best time to climb Chirripó is during the dry season: December through April, with February and March being the driest months. Clear summit views are most likely in the early mornings of this period. The wet season (May through November) brings heavy afternoon rain, more cloud on the mountain, and muddier trails — it is still possible to climb, but visibility at the top is less reliable and the descent more slippery.
For quetzal sightings in the Cloudbridge Reserve, the prime window is March through June, when the wild avocado trees that quetzals feed on are bearing fruit.
Chirripó permits are limited and sell out weeks in advance for peak season weekends. Book through the Sistema Nacional de Áreas de Conservación (SINAC) website as early as possible; weekend dates in February and March go first.