If you have ever camped along the coast of the sea in the winter you are very aware of the cool westerly breeze that blows most early mornings.
In this model animation from ikitesurf.com/WeatherFlow-Tempest you can see the strong El Norte winds that often blow all night in the Sea of Cortez.
However, at 7 AM model animation alsoclearly shows that the winds near shore are much weaker and more from a westerly direction despite the strong northerly winds outside
The morning westerly land breezes on the Baja California Peninsula are driven by the differential heating and cooling of the land and sea, a phenomenon common in most coastal areas.
Part 1 of this blog covers the general factors causing early morning Land Breezes. Part 2 will provide detailed coverage of the land breezes on Baja’s East Cape especially the Rasta Beach, La Ventana and Los Barriles launch sites.
Here’s a breakdown of main factors causing Land Breezes:
1. Nighttime Cooling of the Land
If the skies are clear during the night the land surface cools more quickly than the ocean due to its lower capacity to store heat. You have noticed that land heats fast in during the day while water warms much slower. The same is true when it comes to radiating heat.
So, as the land cools, the air above it becomes denser and sinks, creating a region of higher pressure over the land compared to the ocean.
2. Warmer Ocean Retains Heat
Since the Sea of Cortez waters retains more heat overnight, and the air above it stays relatively warmer, leading to lower pressure over the water.
3. Pressure Gradient
The difference in air pressure between the cooler land (higher pressure) and the warmer ocean (lower pressure) creates a pressure gradient.
4. Breeze Formation
Air flows from the high-pressure area over the land toward the lower-pressure area over the ocean to balance the pressure difference. This creates the westerly land breeze.
5. Geography of Baja California
The peninsula’s long narrow shape amplifies this effect. The proximity of the colder Pacific Ocean to the west and the warmer Sea of Cortez to the east creates sharp temperature contrasts that enhance these breezes.
6. Transition to Daytime Sea Breeze
As the sun rises and the land heats up, this process reverses. The land becomes warmer than the ocean and a local pressure gradient to the Coastal Valleys builds causing a shift to an easterly sea breeze later in the day. However, if there are El Norte winds coming down the Sea of Cortez this same pressure gradient curves the El Norte winds towards shore where they combine with the easterly local sea breezes.
These land breezes are most noticeable during calm, clear nights when other weather patterns (like strong winds or storms) do not dominate.