When to Go
As you might expect, it rains plenty in the Amazon Basin, though that precipitation is somewhat seasonal. Although there's no true dry season in the Iquitos area, it rains less from June to October, when the river’s level drops considerably. For Amazon cruises out of Iquitos, high-water season is best (December–June); tributaries become shallow during the dry months, making it hard to get to oxbow lakes.
The southern Amazon Basin has a pronounced dry season between May and October; and while most lodges are open year-round, some Manu lodges close between December and April. Tambopata sees a well-defined wet season/dry season; Manu's rainfall is more evenly dispersed throughout the year. Plan well in advance for trips in July and August, the peak tourist season, when some jungle lodges often take in large groups and cruise boats can be full. During the dry season, especially July and August, sudden friajes (cold fronts) bring rain and cold weather to Madre de Dios, so be prepared for the worst. Temperatures can drop from 32°C (90°F) to 10°C (50°F) overnight. No matter when you travel, bring a rain jacket or poncho.