On Sunday morning, the Los Osos weather station went from 59 degrees at 10 a.m. to 82 degrees just one hour later and the relative humidity dropped from 98 percent to 40 percent because of the Santa Lucia (offshore) winds.
This warming event should be short-lived, as the ridge of high pressure quickly breaks down today and a trough of low pressure sets up along the West Coast. This condition is expected to produce lower temperatures today.
A shift toward cool and unsettled weather is forecast to begin Tuesday, as an upper-level trough is expected to bring drizzle/
light rain to San Luis Obispo County on Tuesday night into Wednesday morning. Temperatures on Tuesday and Wednesday will drop to slightly below-normal with moderate to fresh (13- to 24-mph) southerly winds. The winds will transition to a more westerly direction by Wednesday afternoon.
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High pressure is expected to rebuild across the Central Coast and should bring normal temperatures with plenty of night and morning low clouds and fog to San Luis Obispo County on Thursday into next Monday.
Tropical Strom Vongfong, north of Okinawa, is forecast to head northeastward and become extratropical as it moves into the Gulf of Alaska next week. This system could produce unsettled weather for the Central Coast the following Thursday and Friday (Oct. 23-24).
Today’s 6- to 8-foot northwesterly (300-degree, deep-water) swell (with a 14- to 16-second period) will decrease to 5 to 7 feet by tonight. A 4- to 6-foot northwesterly (300-degree, deep-water) swell (with an 8- to 14-second period) will develop along our coastline Tuesday and will remain at this height and period through Wednesday.
An 8- to 10-foot northwesterly (320-degree, deep-water) sea and swell (with a 5- to 15-second period) will arrive along our coastline Thursday, decreasing to 4 to 6 feet (with 7- to 12-second period) by Friday.
A 4- to 6-foot northwesterly swell (with an 8- to 11-second period) is forecast along our coastline Saturday through next Monday.
Tropical Strom Vongfong is forecast to produce a 9- to 11-foot northwesterly swell (with an 18- to 20-second period) next Tuesday and Wednesday (Oct. 21-22).
Seawater temperatures are forecast to range from 59 to 65 degrees through Sunday.
PG&E safety tip
During periods of dry and warm weather, always remember to stay hydrated.