The parts separated from the coast by mountains are very dry.
Also because the water off the coast is cold, it never gets very hot and humid at the same time anywhere in the western US. For that you need to be near a large body of very warm water.
Specifically, in all of the west coast of the US except the bottom quarter of CA (where the ocean is a little warmer) the weather is cool and humid when the wind is blowing from the west (which it is most of the time) and dry and potentially very hot when it is blowing from the east.
Well, it is a little more complicated than that because every morning the sun heats the land, but not the ocean, which causes wind to flow from ocean to land, then every evening that flow is reversed, so my previous statement refers to the general flow of air masses in the absence of this diurnal coastal wind.
Also because the water off the coast is cold, it never gets very hot and humid at the same time anywhere in the western US. For that you need to be near a large body of very warm water.
Specifically, in all of the west coast of the US except the bottom quarter of CA (where the ocean is a little warmer) the weather is cool and humid when the wind is blowing from the west (which it is most of the time) and dry and potentially very hot when it is blowing from the east.
Well, it is a little more complicated than that because every morning the sun heats the land, but not the ocean, which causes wind to flow from ocean to land, then every evening that flow is reversed, so my previous statement refers to the general flow of air masses in the absence of this diurnal coastal wind.