When to Visit the Amazon
during the Wet Season
The Wet Season in the Amazon begins by late October and runs to early April. All of the lodges and cruises operate year-round so there's no need to be concerned if you can visit during this time. And hey, it's the rainforest, so rain is definitely something that can come with the territory during any visit. With a little help from lodge-provided rubber boots and ponchos, one might find the downpours an adventure. The balconies on the cruise ships can be covered so sipping a cocktail with a nice meal can still be done as if it were a nice sunny day.
during the Dry Season
Starting by the middle of April and lasting until the middle of October things begin to dry out slightly. The river level will drop providing an increased chance to see wildlife by canoe as caimans and capybaras come down to the river banks to dry out. With it being the rainforest though, rain can come on any day, which just means that visitors would need to make use of the rubber boots and ponchos.
In Peru, the dry season corresponds to the high season in regard to the number of travelers coming to visit. This means you will want to plan in advance as space can fill up early and flights may be more expensive if booked at the last minute.