The Chiriquí highlands have two seasons: the dry season from late December to April, and the wet season from May to November. The dry season is the obvious choice — clearer summit views, easier road conditions, sunny days. The downside is that December and January are also when most Panamanians and Costa Ricans take their highland holidays; Boquete fills up.
The shoulder months of February, March, and April are excellent — coffee harvest is mostly finished, the weather settled, and the visitor numbers easing. The Feria de las Flores y del Café in mid-January is the busiest week.
Even in the wet season the mornings are usually clear; the heavy rain typically comes in afternoon downpours and clears overnight. Quetzal sightings are easier from January through May when the males have their full breeding plumage. For surfing the Pacific lowlands, May to October when the swell comes up from the south is the active season.