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Ecuador Climate
Each region has different factors that affect its climate. The
Costa is influenced primarily by proximity to warm or cool ocean
currents. By contrast, climate in the Sierra varies more as a
function of altitude. The Oriente has a fairly uniform climate that
varies only slightly between the two subregions. Climate in the
Galápagos Islands is both moderated by the ocean currents and
affected by altitude. Throughout Ecuador variation in rainfall
primarily determines seasons. Temperature is determined by
altitude. With each ascent of 200 meters in altitude, temperature
drops 1° C. This phenomenon is particularly significant in the
Sierra.
The Costa has a tropical climate. Temperatures for the region
as a whole remain fairly constant, ranging from 23° C in the
south
to 26° C in the north. Although seasonal changes in temperature
are
not pronounced, the hottest period occurs during the rainy season,
especially from February to April. Near Guayaquil, the coolest
months are August and September. Rainfall in the Costa decreases
from north to south, with vegetation changing from tropical
rainforest in the north to tropical savannah to desert in the
south.
Differences in temperature and rainfall in the Costa are caused
by the Peruvian Current and periodic appearances of El Niño. The
Peruvian Current, also formerly known as the Humboldt, is a cold
ocean current that flows north along the coasts of Chile and Peru.
At Cabo Blanco, where the Gulf of Guayaquil begins, the main
current veers to the west; a branch continues northward to Cabo
Pasado, in Manabí Province, where it also turns westward to merge
with the main current near the Galápagos Islands. The cold water
and air temperatures associated with the Peruvian Current inhibit
rainfall along the coast, creating dry to arid conditions. This
effect is greatest along the southern coast of Ecuador.
The El Niño occurs periodically every six or seven years.
Starting in late December, a change in atmospheric pressure shifts
ocean currents so that warm waters come closer to shore and
displace the cold waters. During this time, air and water
temperatures, tides, sea levels and wave heights, and relative
humidity all are higher than usual. These conditions produce heavy
rainfall that generally lasts until May in an area that normally
experiences nothing more than a drizzle. The resulting flooding and
landslides can be devastating.
When the Peruvian Current is dominant, the amount of
precipitation along the coast varies from north to south, with
levels ranging from 300 centimeters to 30 centimeters,
respectively. Two rainy seasons in the northernmost part of the
coast become a single season (December through June) not far south.
Near Esmeraldas, average annual rainfall is 250 centimeters. The
rainy season shortens farther south, lasting only from January to
May at Guayaquil. Very little rainfall occurs on the end of the
Santa Elena Peninsula west of Guayaquil. Arid conditions prevail on
the border with Peru south of the Gulf of Guayaquil.
Separated from the effects of ocean currents by the Cordillera
Costañera, the Costa Internal has a hot and humid climate.
Temperatures can surpass 26° C, and the vegetation and cloud
cover
tend to retain and augment the heat. Rain is constant during the
winter months of December through May, with the heaviest rainfall
occurring in February and March.
Temperatures in the Sierra do not vary greatly on a seasonal
basis; the hottest month averages 16° C and the coolest month,
13° C
in the upper elevations. Diurnal temperatures, however, vary
dramatically, from cold mornings to hot afternoons. The almost
vertical sun and the rarified air in the higher Sierra region allow
the land to warm quickly during the day and lose heat quickly at
night. Mornings typically are bright and sunny, whereas afternoons
often are cloudy and rainy. In general, rainfall amounts are
highest on exposed locations at lower altitudes. Rain also can vary
on a local basis. Sheltered valleys normally receive 50 centimeters
per year, whereas annual rainfall is 150 centimeters in Quito and
can reach 250 centimeters on exposed slopes that catch rain-bearing
winds. On a seasonal basis, the driest months are June through
September.
Climate in the Sierra is divided into levels based on altitude.
The tropical level--400 to 1,800 meters--has temperatures ranging
from 20° C to 25° C and heavy precipitation. The
subtropical level--
1,800 to 2,500 meters--has temperatures from 15° C to 20°
C and
moderate precipitation. The temperate level--2,500 to 3,200 meters-
-has a year-round temperature in the range of 10° C to 15°
C and an
annual rainfall of 100 centimeters. The temperate level experiences
rainstorms, hailstorms, and fog. Winter, or the rainy season, lasts
from January through June, and the dry season or summer from July
through December. Most rain falls in April. There also is a short
rainy period in early October caused by moisture penetrating the
Sierra from the Oriente. Quito and most other populated areas in
the Sierra are located at this temperate level. The cold level
extends from the temperate zone to 4,650 meters. Here, average
temperatures are 3° C to 9° C, and the precipitation often
appears in
the form of rain, hail, and thick fog. Above 4,650 meters is the
frozen level, where peaks are constantly capped with snow and ice,
and temperatures range from below zero to 3° C. Precipitation
frequently is in the form of snow, fog, and rain.
The Eastern lowlands in the Oriente experience an equatorial
climate. Rainfall is abundant, especially in the Andean piedmont,
sometimes exceeding 500 centimeters per year. Temperatures average
25° C in the western parts of this region. The jungle-covered
plains
of the Eastern lowlands register high levels of rainfall and
temperatures surpassing 28° C.
Being located on the equator, the Galápagos Islands would have
an equatorial climate were it not for the modifying effects of the
Peruvian Current. Instead, climate on the islands follows a pattern
more like that of the Sierra than the Costa. At sea level, the land
is desertlike with temperatures of 21° C. The eight summer
months
experience no precipitation, whereas the winter months of January
through April have some fog and drizzle. Above sea level to an
altitude of 450 meters, the islands have a mixture of tropical,
subtropical, and temperate climates. In general, temperatures are
around 17° C. There is constant fog and drizzle in the summer
and
rain in the winter. The cold level above 450 meters has
temperatures below 14° C.
Data as of 1989
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