Differential heating of land and ocean changes the air pressure gradient.
San Fernando Valley gets hotter and air rises over it, so air pushes in around the mountains from L.A. and O.C. coastal plains.

In Eaton Canyon, Pasadena, on most of our sunny field trips, we feel ocean breezes coming in from the SE because of the way the cliff walls are angled.

This aerial photo is angled so NW is at the top.

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Here are current National Weather Service links for SFV so you can see if this is happening whenever you read this. “Inland Valleys”:
San Fernando ValleyNorthern – San Fernando (Camp 9): http://www.wrh.noaa.gov/mesowest/getobext.php?wfo=lox&sid=CNIC1&num=168&raw=0&dbn=m
SE SFV – Burbank Airport: http://www.wrh.noaa.gov/mesowest/getobext.php?wfo=lox&sid=KBUR&num=168&raw=0&dbn=m
SW SFV – Chesebro: http://www.wrh.noaa.gov/mesowest/getobext.php?wfo=lox&sid=CEEC1&num=168&raw=0&dbn=m

Pasadena’s is Santa Fe Dam, so topographic steering around Eaton Canyon cliff walls doesn’t show in the records: http://www.wrh.noaa.gov/mesowest/getobext.php?wfo=lox&sid=STFC1&num=168&raw=0&dbn=m.
Remember to study the times of day, because NE ones are during the nighttime hours, downslope mountain winds.

Catalina Eddy circulations (aka ‘coastal eddy’) also bring SE winds on gray days.

http://www.scwxa.org/eddydemo.jpg