The National Weather Service out of San Diego on Saturday issued a Red Flag warning from 7 p.m. Sunday evening through 4 p.m. Monday afternoon for the Santa Ana Mountains of inland Orange County due to very low relative humidity and gusty Santa Ana winds expected to blow east-to-northeast.
Orange County coastal areas so far remain on a Fire Weather Watch, which is less severe than a Red Flag event. The coastal region may experience strong gusty winds, possibly up to 25 MPH, while the Santa Ana Mountains could experience gusts of up to 45 MPH.
The culprit is a typical autumn high pressure system over inland deserts, which act like a giant wind blower to shove dry desert air towards the
ocean. As the air gets compressed, as it squeezes through local mountains, it gets even hotter and drier.
High temperatures Monday may hit the low 90s, and relative humidity readings could drop to 7 percent, the NWS warned.