galapagos weather

Weather
These satellite maps show chlorophyll concentration (which corresponds with the abundance of phytoplankton) during El Niño (top) and La Niña (lower). Blue represents low concentrations, yellow, orange and red indicate high concentrations. Currents that normally fertilize the phytoplankton reverse during El Niño, resulting in barren oceans. These same currents are strengthened by La Niña resulting in an explosion of ocean life.
The bottom image shows sea surface temperature, cool up welling waters are coloured purple. Thriving phytoplankton populations are indicated by high chlorophyll concentrations (top image), coloured green and yellow. Images acquired on March 2, 2009.

Although located on the Equator, the Humboldt Current brings cold water to the islands, causing frequent drizzles during most of the year. The weather is periodically influenced by the El Niño phenomenon which brings warmer temperatures and heavy rains.

During the season known as the "Garua" (June to November) the temperature by the sea is 22°C (71.6°F), a steady and cold wind blows from South and Southeast, and frequent drizzles (Garuas) last most of the day, along with dense fog which conceals the islands. During the warm season (December to May) the average sea and air temperature rises to 25°C (77°F), there is no wind at all, there are sporadic though strong rains and the sun shines.

Weather changes as altitude increases in the large islands. Temperature decreases gradually with altitude, while precipitation increases due to the condensation of moisture in clouds on the slopes. There is a large variation in precipitation from one place to another, not only with altitude but also depending on the location of the islands, and also with the seasons.

The following table corresponding to the wet 1969 shows the variation of precipitation in different places of Santa Cruz Island:
Location Charles Darwin
Station Devine Farm Media Luna
Altitude 6 m 320 m 620 m
January 23.0 mm 78.0 mm 172.6 mm
February 16.8 mm 155.2 mm 117.0 mm
March 249.0 mm 920.8 mm 666.7 mm
April 68.5 mm 79.5 mm 166.4 mm
May 31.4 mm 214.6 mm 309.8 mm
June 16.8 mm 147.3 mm 271.8 mm
July 12.0 mm 42.2 mm 135.6 mm
August 3.8 mm 13.7 mm 89.5 mm
September 18.5 mm 90.9 mm 282.6 mm
October 3.2 mm 22.6 mm 96.5 mm
November 11.0 mm 52.8 mm 172.7 mm
December 15.7 mm 84.1 mm 175.3 mm
TOTALS 469.7 mm 1901.7 mm 2656.4 mm

The precipitation also depends on the geographical location. During March 1969 the precipitation over Charles Darwin Station, on the southern coast of Santa Cruz was 249.0 mm, while on Baltra Island the precipitation during the same month was only 137.6 mm. This is due to the fact that Baltra is located behind Santa Cruz with respect to the prevailing southerly winds, so most of the moisture gets precipitated in the Santa Cruz highlands.

There are significant changes in precipitation from one year to another too. At Charles Darwin Station the precipitation during March 1969 was 249.0 mm, but during March 1970 it was only 1.2 mm.