Mexico does not have nautical weather reports. The best bet is Ham cruiser nets. There are three of them that provide weather forecasts of the Sea of Cortez. While in La Paz, the Cruiser''s net on VHF hand down the ham forecasts to the fleet.
Email me directly and I''ll send you the ham frequencies to monitor. You''ll need an HF receiver to listen in.
I was mistaken about the number of moblile cruising nets operating in the Sea of Cortez. There are five. For net frequencies and other important stuff, tune in to wibe site cruisecortez.com. This site is the most informative for the Sea of Cortez. Detailed descriptions of various ports of call and anchorages are available. Communications and documentation is discussed in detail. Net weather of major airports is also available linked to this site.