The warmest time is December to May. June to September offers cooler and drier conditions for trekking the Andean highlands around Quito. Humpback whales also migrate along the Pacific coast during this time. October and November bring fewer tourists and variable weather—like sunny mornings and rainy afternoons. The western Amazon region is always wet, but less so August to November. The Galápagos is spectacular year-round, and if you’re on a multi-day cruise that restricts visitor numbers, you can snorkel the clear waters during the warm season of December to May and hardly notice that this is also the most popular time.