Almost every evening the wind blows from the SSW during the spring and early summer in the Bay of La Paz Coromuel winds area a welcome and unique phenomenon of the La Paz area. These south-to-south west winds begin in the late spring and continue for most of the summer months. They generally begin to blow an hour or so before sunset and continue through the night till mid morning. These winds are created by the cool marine air from the Pacific side of the peninsula being drawn over the desert to the relatively warmer side of the Sea of Cortez.
The winds are noted from the Cerralvo Islands to Agua Verde and can be particularly strong in the San Lorenzo Channel. These cooler winds bring great relief to those residents of the La Paz area except for during the hottest months of September and August when the relative temperature difference between the two sides of the peninsula is not that great. The winds on the average blow 10-15kts maybe up to 40 mph at the strongest. Winds diminish as the Sea of Cortez warms and nighttime temperatures vary less dramatically. There are even more specific geographical effects.
The area at the northeast side of Bahia de La Paz seems to funnel hot air from the deserts into the Sea nearly year round. Playa Tecolote and Bahia Balandra experience SW winds nearly every night of the year. Although this can make anchoring more tenuous for cruisers, it also keeps the no-see-ums and other flying insects at 'bay'. The winds can make anchoring along the western side of Espiritu Santos a challenging experience as well. With only one anchorage, Partita well protected and Ensenada Grande somewhat protected other anchorages at the island can make for a long night. Anchorages like El Cardinal can point directly into the building Coromuels and 3' rollers reflect around the small area. Late in the spring many boaters choose to anchor on the north/east side of Partita after the threat of north winds has passed during the day. The name of these winds has an interesting history.
There are many stories of how this consistent wind was used by the English pirates to attack Spanish trade in The Sea. The winds are named for the Lord Protectorate of England, who issued many letters of Marquee for privateers in the region. Another version is that the pirates used these winds to escape the Bay with the stolen pearls from the resident Indians that lived around the bay (yes, La Paz had real pearls but that is another story. In any case, most of the stories include the English and pirate of some sort, even though when researching this subject there was no evidence English ships of that era made it this far north in the Sea. Whatever is the truth concerning the naming of these winds may be augured they definitely exist and are very consistent and regular.
If you are a sailor and plan your trip to the islands right you can sail downwind to the islands in the early morning or late evening hours and return with the north-northwest wind at your back in the mid day! One of the tricks I have learned over the years is to keep an eye on the land behind La Paz if you are sailing in, in the late afternoon. Many times you will see a substantial dust cloud behind the city in the desert which is a sign the winds are coming in the next half hour to an hour and that not only will the direction change but the speed will increase dramatically. Happy sailing and stay cool thanks to the Coromuel.