Predominate in the third quarter of the year the Humboldt Current runs up the west coast of South America from Antarctica. [This current is what brought penguins and fur seals to the Galapagos
As the Humboldt Current moves through the islands during the 3rd and 4th quarter from June to November, it cools temperatures. The winds come from the southeast and create an inversion over the area. Low straight formed clouds cover the islands much of the day. A drizzle known as garua
occurs in the highlands. The garua
visibility is lower than the warmer months. Though there is more frequent precipitation this time of year the light rain made it difficult for settlers to collect water during this season. This time of year is referred to as the dry season
Water temperatures during the cooler months of August and September range from 60° to 65°F [16° to 19°C
] in the western islands to around 78°F [25°C
] near Darwin and Wolf at the far north of the archipelago. The average water temperature is 70°F [21°C
]. From October to December the water temperature drops to the between 60° to 70°F [16° to 21°C
These later months are a good time for green sea turtle sightings [during their mating season
] and shark sightings are still high, but rays are seen less frequently.
In November as the Humboldt Current leaves the Galapagos the warm waters from the Panama Current come to ta ke their place. These warm waters dominate the climate in the islands from January to May.
During these months the water temperatures rise to 70° to 80°F [21° to 27°C
]. The air temperatures, which are no longer cooled create an inversion layer. The skies are clear and visibility is increased.
The marine life is excellent with many shark, ray and schooling fish sightings. This time of year the waters tend to have the best visibility and the best time of year for diving and snorkelling.
El Nino Current
Every 2 to 7 years the strong westward-blowing trade winds subside. These winds, which normally pull the warm waters to the west and allow the nutrient rich Humboldt Current to reach the Galapagos, fail to leave the islands. Instead the warm water slowly moves back eastward across the Pacific. The food chain is broken and the breeding cycle of many of the animals including;
Galapagos Penguins and Marine Iguanas , which feed off the upwelling
is interrupted. Warmer water temperatures also cause an increase in the mortality rate of the young birds and animals. Plants, on the other hand, seem to thrive during El Nino years. Plants, which may not have flowered in years, will flower again due to the excess water.
Peruvians named this phenomenon El Nino, for the Christ child, because it first appears around Christmas. Major El Nino Currents occurred as recently as 1982 and 1998.