May and June have low clouds

Clouds are low during May and June, for three reasons:

1. Convection.

2. High pressure (the east Pacific high) builds into our region and the high is associated with sinking motion.

3. The earth is warmer than the ocean, so warm continental air moves over cold water, and gets cooled to its dew point.

And global climate change is going to make this more persistant!

http://cliffmass.blogspot.com/2011/05/june-gloom-and-kuow-weekday.html