During the garúa season, which typically lasts from July through December, temperatures are lower than they are during the rest of the year. Cold waters come up from the Antarctica region, carrying with them the makings for a subtropical, rather than tropical climate. A fine, misty rain (or garúa) blankets the tops of the islands, which turn lush and emerald green.
The hot/rainy season runs from January to June. In the first three months of the year, the annual rains arrive; they are strong but of short duration. Temperatures rise, and sunny days are frequent. Warmer waters head south from Panama and Columbia, making this for some, a favorite time for snorkeling.
However, the varied natural changes the two seasons bring to the appearance and fauna of the islands mean that there's never a bad time to see and visit the Galápagos. The "peak season" is sometimes described as mid-June through early September and from mid-December through mid-January. But since the Galápagos National Park Service implemented restrictions on the number of visitors to each island at any one time, you will never feel as if you're one in a throng of people. At any time of the year, you'll be sure to feel as if the islands are yours alone, or yours and a few good friends to enjoy in peace and natural solitude.