Offshore Winds in California During the Dry Season*

(Santa Ana in southern California; Diablo in north-central California)

(Note: Santa Ana/Diablo Wind Pattern can occur during the Fall, Spring or Winter, but only in the late Summer and Fall does it occur when vegetation is dried out from the normal summer dry season, making fire hazard extremely high. Also, only during the late Summer and Fall is the air that makes it to the coast warm to begin with over the Great Basin, so that it arrives warm to hot at the coast. In the midwinter, the pattern may occur, but the air in the Great Basin is so cold to begin with, that when it warms compressionally it is still cool compared to normal temperatures at the time)

I. Are "Hot" Because

Air that is warm to begin with is further warmed by compression.

II. Are "Dry" Because

Air with little water vapor to begin with is warmed furtther, thus, further lowering relative humidity.

III. Are associated with very strong surface wind speeds because

Very fast wind speeds occur downwind of major canyons and over ridges and on downwind slopes.