Barometric Pressure Forecast for Murrieta, California
Barometric pressure forecast for Murrieta, California — in the Temecula Valley of southwestern Riverside County, inland of the Santa Ana Mountains. See current barometric pressure and what it means for weather-sensitive people.
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Pressure and weather in Murrieta
Murrieta sits at about 1,100 feet in a valley bounded by the Santa Ana Mountains to the west and the higher desert country to the east, roughly twenty-five miles from the ocean but separated from it by a substantial ridge. A gap in that ridge, the canyon carved by the Santa Margarita River, is the one route by which marine air reaches the valley, and on summer nights it funnels cool ocean air inland and drops temperatures far faster than places just a few miles away. The pressure year has two acts. From December through March, Pacific storm systems reach Southern California and deliver the region's only sustained falls, typically eight to eighteen hPa, though in dry winters there may be only a handful of such events in a season. From September into December the pattern inverts: high pressure builds over the Great Basin, a strong offshore gradient develops between the interior and the coast, and Santa Ana winds accelerate through the mountain passes, with the same Temecula gap that admits cool air at night now channelling hot, desiccating downslope wind the other way. Those weeks combine a high, rising barometer with single-digit humidity and extreme fire danger, and it is the gradient rather than the absolute reading that drives the wind.
What this means for you
Winter storms and autumn Santa Ana gradients are the two things that move the reading here. Checking the barometric pressure forecast during a Santa Ana spell explains a wind that seems to come from nowhere.