79 degrees at 2 a.m.? Why SLO County saw a weird temperature spike overnight
It was unusually warm in some parts of San Luis Obispo County last night, as temperatures managed to hit upwards of 70 degrees in some areas.
According to meteorologist John Lindsey, winds sweeping from the Cuesta Grade late Thursday and early Friday pushed temperatures into the low to high 70s overnight — an unusual occurrence when earlier in the week folks were pulling out their sweaters and fall gear.
“If you found yourself kicking off the blankets and wondering why it felt so warm in San Luis Obispo, Morro Bay, and Los Osos last night, here’s the reason,” Lindsey wrote in a post on X on Friday. Lindsey said temperatures hovered at near 58 degrees at the top of the Cuesta Grade on Thursday night. But as Santa Lucia winds swept down from the northeast, they began warming at a rate of about 5.4 degrees per 1,000 feet of descent.
“By the time the air reached the valley around 2:00 a.m., the temperature had climbed to about 70°F,” Lindsey wrote. “In fact, a few spots along the west side of the Santa Lucia Mountains even hit the mid-70s — a perfect textbook example of adiabatic warming in action.”
According to the NOAA, adiabatic warming is when the temperature of a body of air increases because of compression as it descends in the atmosphere, with no exchange of heat with the surrounding air.
A map of the area Lindsey shared showed parts of Morro Bay hitting the low 70s — and one spot in San Luis Obispo even hitting a recorded 79 degrees — even as temperatures remained at a much more seasonal 50s-to-60s range in the North County.
The strange phenomenon does not appear likely to continue through the weekend.
According to the National Weather Service, overnight temperatures are expected to range from a low of 52 degrees in San Luis Obispo to 53 degrees in Morro Bay through the weekend.
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