Huánuco's climate is famously mild — at 1,800 metres in a sheltered valley, it avoids both the cold of the high Andes and the heat of the lowlands. Average temperatures hover around 22-25°C year-round, with cool evenings. The city gets its nickname "city of eternal spring" from locals who consider it one of the most pleasant climates in Peru, and for once the local boasting has some basis.
The dry season runs roughly May to October and is the best time to visit: clear skies, passable roads into the mountains, and easy access to Kotosh and the Carpish area. The wet season (November to April) brings daily afternoon rains that make highland roads muddy and the Carpish cloud forest even more atmospheric, though travel is less predictable.
The fiesta of El Señor de Burgos in late January is the city's main celebration, with processions, music, and dancing filling the plaza for several days.