Page "Colorado Desert" Paragraph 7

The west coast Peninsular Ranges, or other west ranges, of Southern California – northern Baja California, block most eastern Pacific coastal air and rains, producing an arid climate.

Other short or longer-term weather events can move in from the Gulf of California to the south, and are often active in the summer monsoons.

These include remnants of Pacific hurricanes, storms from the southern tropical jetstream, and the northern ITCZ.