What are the 3 climate zones of West Coast U.S?

1 Answer
Jan 28, 2018

The three climate zones of the US West Coast are:

  • #"Marine West Coast"#
  • #"Mediterranean"#
  • #"Midlatitude desert"#


Here is a map showing the climate zones of the United States

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Looking at the West Coast, you can see three climate zones.

From north to south, they are

  • #"Marine West Coast"# (dark green)
  • #"Mediterranean"# (orange)
  • #"Midlatitude desert"# (yellow)

#color(white)(mmmmmmmm)# ———————————

#color(white)(mmmmmmmm)##"Marine West Coast climate"#

Characterized by equable weather with few extremes of temperature, and ample precipitation in all months, this climate type is located north of the Mediterranean climate region on the western sides of the continents.

In North and South America, Australia, and New Zealand, north–south mountain ranges such as the Rockies enhance precipitation, but confine the marine west coast climate to relatively narrow coastal strips.

Annual precipitation is plentiful, reliable, and frequent.

  • Many areas have rainfall on more than 150 days per year.
    Accumulations generally range from 20" to 100", and up to 200" where onshore winds encounter mountain ranges.
    Fog is common in autumn and winter, but thunderstorms are infrequent.

Annual temperature ranges are rather small.

#color(white)(mmmmmmmm)# ———————————

#color(white)(mmmmmmmm)##"Mediterranean climate"#

A Mediterranean climate is mild, with few extreme temperatures, so it really has only two seasons: summer and winter. Summers are longer than winters, and the winters are very mild. Very few places experience snow in a Mediterranean climate.
This climate is often found on the western sides of continents.

The cause of this climate is directly related to large bodies of water and ocean currents. Ocean currents shift as the seasons change.

During the summer, cold currents keep the climate mild and dry.
During the winter the water that was warmed up all summer moves in and keeps the land warm, often bringing rain.

Annual precipitation is rather low.

  • The Mediterranean climate is fairly dry, averaging around 20" of annual rainfall. During the summer, cold ocean currents bring dry air with almost no precipitation. During the winter, the currents shift and warmer, moist air brings rain.

Annual temperatures range between warm (or hot) dry summers and mild (or cool) wet winters.

#color(white)(mmmmmmmm)# ———————————

#color(white)(mmmmmmmm)##"Midlatitude Desert Climate"#

The midlatitude desert climate is found in the Great Basin of the United States. Here, east facing slopes lie on the leeward sides of mountains in the rain shadow of the westerly winds.

The midlatitude desert lies in a region where high-level subsidence, especially pronounced in the summer, inhibits precipitation. During the winter, these regions are effectively cut off from moist air masses, so cold high pressure dominates the region.

Annual precipitation is sparse, irregular, and unreliable.

Temperature has large daily ranges.

  • Like its tropical equivalent, the midlatitude desert has lots of
    sunshine throughout the year with few clouds. The large daily temperature ranges are due to cloudless days and nights.

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You can find out more about the US west coast climate zones here: