December is good for cooler-than-usual temperatures. This is the hottest part of the country; daytime temperatures are just above 30°C (86°F) almost year-round, spike in sweltering April and dip into the relatively cool mid-20s °C (mid-70s °F) in December.
October and November are the peak months to see nesting turtles at the Reserva Natural Estero Padre Ramos; the whole season lasts between July and December. This is also a good time to think about volunteering as a beach warden or visiting Reserva Natural Isla Juan Venado.
Semana Santa is held in late March to early April – Easter week is a technicolor dreamscape in León. There are sawdust 'carpets' in colonial suburbs, and a sand-castle competition at a nearby beach.