Today we’re going to go back more than a century and a half to a hot summer day on the central coast of California, to the town of Santa Barbara. June 17, 1859 began as a summer day much like any other, clear with plenty of warm sunshine, plus a cool breeze to make it just perfect. But according to legend, something happened that wrought sudden death and destruction: from out of nowhere, a wind with temperatures usually reserved for baking ovens blasted down from the hills, killing animals and injuring people. It immediately set the country’s highest recorded temperature. They named it the simoom, after the hot Sahara wind of the same name. But it turns out that data is hard to come by. Was the Santa Barbara simoom a true freak of nature, or perhaps merely a tall tale told to visitors?
Here is a snippet about the 1859 simoom from the Insider’s Guide to Santa Barbara:
Until 1934, Santa Barbara had a record high temperature on the U.S. Weather Bureau’s books. On June 17, 1859, a simoom (scorching wind) swept down from the northwest, and the mercury soared to 133° Fahrenheit (about 56° Celsius). Cattle dropped dead, and birds fell from the sky. The record was topped when the mercury hit 134° Fahrenheit (about 57° Celsius) in Death Valley in 1934.
It sounds a bit like a tall tale, a perfect subject for our skeptical eye.
Sudden, hot winds are absolutely a reality on the California coasts. They’re called the Santa Ana winds, and are the main contributors to the wildfires that can so often be so destructive to coastal communities. Dry air from the Mojave Desert and even the Great Basin further inland forms a high pressure region which cools, sending it spilling downhill toward the coast. The wind is very dry and gusts can reach hurricane forces at their strongest. The wind is usually hot, but not because it came from the desert; it gets heated on the way by adiabatic forces; basically, compression. Santa Ana winds can happen at any time of year, but are most common in the late autumn and early winter.
Although Santa Barbara is a ways up the coast from the Santa Ana winds, it is indirectly affected by them. The high pressure systems that create the Santa Anas are usually moving east, so a few days before they collapse into Santa Anas, they often cause a similar phenomenon in Santa Barbara that locals call the Sundowner. When the Sundowner winds spill over the Santa Ynez mountains and rush to the sea, they can wreak some havoc; but because their path is much shorter, adiabatic compression forces don’t have as much opportunity to heat the Sundowners as much as their more southerly cousins.