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All About Santa Ana Winds

October 14, 2018
By WeatherBug Meteorologist, Chad Merrill

A common weather occurrence this time of the year, the Santa Ana winds will be active early this week. Santa Ana winds refer to a usually very hot and dry wind that blows from interior regions towards the coastline. While blowing dust is a pesky side-effect of these winds, the most publicized effect of the Santa Ana winds is their ability to quickly spread fires and knock out power.

The origin of the Santa Ana name comes from the fact that these winds blew through the Santa Ana valley, affecting early settlers of the area. A popular misconception is that the winds were named after the Mexican president and general, Antonio Lopez de Santa Ana. Because the winds were referred to as Santa Ana winds before the president was famous, this naming origin has been discounted.

These winds usually develop when a large ridge of high pressure develops over the Great Basin, an area located over much of central Nevada. The clockwise wind flow around this high pressure system brings an east-to-west wind to the Desert Southwest.

As these winds surge towards the coastline, they flow down the Sierra Nevada, San Gabriel and the San Bernardino mountains. In addition to an increase in forward speed, the winds traveling down these mountain ranges are compressed and warmed.

With the compression and warming, much of the moisture is removed from the fast-moving airmass. The relative humidity within these winds often drops below 20 percent, helping to dry out vegetation in the path of the winds. Temperatures often soar into the mid 80s and lower 90s during these events. However, some Santa Ana events in winter often don't produce such a temperature spike.

The hot, dry nature of these winds, combined with gusts anywhere from 35 to 55 mph, create a hazardous wildfire potential. In the event that a fire is ongoing, the brisk winds tend to quickly fan the flames, making it difficult for firefighters to get control of the blaze. When the Santa Ana winds eventually reach the Pacific Ocean, they usually result in choppy surf conditions along the coastline.

Highest gusts within these winds are often observed during the overnight and morning hours, when the onshore sea breeze is dormant and not acting against the Santa Ana winds.