The Galapagos Islands are a year-round destination with perfect holiday weather; wildlife is bustling all over the year, and each season has its own charm. The overall climate is quiet and warm, and unusual dry for the tropics, saving local micro-climates in the moist highlands. The weather is calm as well; the islands aren’t located on the path of cyclones or tropical storms.
Although this archipelago is situated on the equator, actually the climate can only be characterized as tropical in the first half of the year. This ‘hot season’ never gets excessively hot, but counts with a very intense equatorial sun, blue skies, alternated with some rain or even an occasional shower. From about June onwards to the end of the year is the cooler, dryer and overcast ‘garúa season’. Although called ‘cool season’, these months still count most of the time with nice summer weather, and give the opportunity to avoid the most intense sunshine.
The overall climate of these Pacific islands is regulated by an interplay of no less than five ocean currents that meet. Most influential players are the cold Humboldt Current, arriving from the Antarctic and the tropical Panama and Equatorial Counter Currents.
In the cool season, roughly between June and November, the south-eastern trade winds boost dominant cold waters from the south to Galapagos, chilling air and water temperatures. These rich waters also bring large quantities of food for sea birds and their chicks. Condensation at an altitude of just 300-600 m (1000-2000 ft) forms a light overcast (especially in July and August) that usually is broken open by the burning afternoon sun. In the south-eastern highlands these clouds appear as a fine drizzling fog, locally known as garúa. In August and September the sea becomes somewhat rougher as well.
In the hot season, from December till about April, the trade winds calm and the Humboldt Current is no longer strong enough to invade the tropical waters of the Pacific currents. Supported by prevailing eastern winds, warmer waters enter the archipelago (comfortable for snorkeling). Moist air can evaporate freely and clear the overcast, but form higher rain clouds while day temperatures rise. Highest temperatures are in March (sometimes over 30˚C or 86˚F). Seas generally are at their calmest as well from January to April.
During the transitional months weather is changeable, and shows the characteristics of both seasons. The start of each season tends to vary yearly and the change can take over a month.
Every few years (irregular) the tropical currents are more powerful and cause a climate phenomenon that is called ‘El Niño’, after the Christ-child, both born end of December (last occurrences in 1997-1998, 2002-2003, 2004-2005, 2006-2007 and 2015/2016). The causes are not fully understood yet and serious matter of scientific investigation. But the consequences may be severe for human, marine and sea bird life, although present Galapagos species proofed to be able to survive longer periods of considerably warmer waters and scarce food. Nevertheless especially Galapagos penguins and flightless cormorants are very vulnerable to this phenomenon, while the bigger populations of Galapagos sea lions and blue-footed boobies suffer as well. Land birds on the other hand thrive during ‘El Niño’-years.
Within this general climate story Galapagos owes its wealth and variety mainly to its diverging micro climates. It counts no less than 7 different climate zones, contributing to Ecuador’s amazing biodiversity! While the south-eastern highlands receive most rain and are covered by dense escalesia cloud forests, the northern slopes lie in the rain shadow and have a completely different look.
The same applies to sea water temperatures. These tend to vary strongly locally, ranging from 16˚C-28˚C (60˚F-82˚F) at the surface, depending on the season, the depth of the water, currents, among other factors. West from Isabela, where the Cromwell Current wells up from the deep sea, snorkeling waters are coldest and a wet suit is recommended to be able to stay longer in the water (and for divers: Darwin and Wolf are surrounded by very cold waters).
Although Galapagos may have calm and perfect holiday weather, the hard reality is that its climate is tough for species that have to cope with it; and it is a critical element for natural selection; not only because of lack of fresh water, but for dramatic climate changes as El Niño as well.