Copán sits in a high valley at about 640 metres elevation, which keeps temperatures mild year-round — warm days, cool evenings. The dry season runs from November through April and is the most comfortable time to visit: the site paths are dry, the forest around the ruins is accessible, and there is no risk of rain interrupting an outdoor day.
The wet season (May through October) brings afternoon rains that cool the air but can make the site's earth paths muddy and the jungle vegetation dense. Morning visits avoid the worst of the rain and the crowds (which, even in peak season, are modest compared to Chichén Itzá or Machu Picchu). The site is never genuinely crowded.
December through February is the busiest period for North American and European tourists. Guatemalan and Honduran visitors tend to come in the Easter holiday period (Semana Santa) and in July and August. At most times of year, the archaeological site has a pleasantly manageable number of visitors.