The Galapagos Islands are primarily affected by weather systems which come from the east. Located on the equator 600 miles west from mainland South America, the weather in the Galapagos Islands is influenced by the position of the Inter-Tropical Convergence Zone (ITCZ). The ITCZ is the climatic equator where the winds from the north meet the winds from the south. This is where the infamous “doldrums” take place at times when the air stills, thunderheads can be seen. Although extremely rare, during your Galapagos Cruise, the occasional lightning flash can be seen and heard during strong “El Niño” years.
Due to the rotation of the earth and its position on the equator, in Galapagos the winds arrive from either from the northeast, called the Northeast Trade Winds, or from the southeast, known as the Southeast Trade Winds. To “blow trade” means to blow constantly, useful to know in the days of sailing vessels plying the oceans of the world. The ITCZ is not positioned exactly over the geographic equator, but lies generally about 100 nautical miles to the north. This climatic equator, however, moves north or south according to the time of year and the tilt of the earth. At its most northerly position it lies over parts of Central America. At its most southerly position, over the Galapagos Archipelago.
In the Galapagos Islands, January to May is known as the warm, wet season when the ITCZ moves to its most southerly position. Although every year has its own personality, these months are generally known to have a higher humidity (around 80%), and heavier, sporadic rainfall. Although air temperatures are not as high as one would imagine, the humidity can make the mid-80’s F (30ºC) weather feel warmer than it really is. The rainshowers generally only last for a short time and then Galapagos enjoys glorious sunny skies of blue. The waters at this time of year are generally warm, in the low to mid-80’s F (22-25º C), and visibility is at its best for snorkeling and diving.
From Late June to November, Galapagos weather is influenced by the Humboldt Current which brings cooler waters and nutrients up along the western coast of South America. This time of year has the most comfortable air temperatures around the islands due to the lower humidity. Usually T-shirts and shorts are fine for the low to mid-70’s F (22ºC), with even the occasional windbreaker needed for early mornings or late afternoons on shore. Water temperatures drop to around 65-70ºF (18-20ºC), for which on our Galapagos cruise we provide our guests with short wet-suits.
During the “cool” season, an “inversion” layer forms low, grey clouds that occasionally can roll in and out all day. Air heated by the intense equatorial sunlight rises, then falls as it begins to cool. As the heavy, moisture-laden air descends, they encounter the cooler Southeast Trade Winds on the ocean surface pushing the Humboldt current up the west coast of South America and west to the islands.
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