Temperatures in Orinda are forecast to hit 94°F on Tuesday, Aug. 4, with the National Weather Service warning that offshore winds and extreme heat will push fire danger across the East Bay hills to elevated levels through the weekend of Aug. 8–9.

The NWS issued a heat advisory Monday, Aug. 3, covering the East Bay hills and valleys with highs of 95 to 105°F. That advisory ran from 10 a.m. to 10 p.m. Monday. But the broader concern extends well beyond one day: the Weather Service forecasts that high temperatures later in the week will combine with offshore wind events to sustain fire risk into the weekend.

The NWS described the East Bay as the hottest sub-region in the Bay Area for this event, with maximum temperatures in the mid to high 90s expected across the Tri-Valley, according to Bay City News reporting published Monday, Aug. 3. Minimum relative humidity is forecast to drop below 30% around Mount Diablo and Altamont Pass, conditions the Weather Service calls above-average dry with increased fire potential.

Central Valley winds pushing dry air westward, driven by a re-strengthening heat dome southeast of the Bay Area, are creating the conditions, KRON4 reported. The NWS warned of a near-critical fire weather threat across the East Bay and Diablo Range, with weak offshore flow expected to keep vegetation dry.

Recent fires underscore the risk

Two fires in the past week illustrate what elevated conditions mean locally. A third-alarm fire heavily damaged the former Henry J. Kaiser Estate, a 14,000-square-foot mansion at 940 Reliez Station Lane in Lafayette, on Saturday, Aug. 1. No injuries were reported. Deputy Fire Chief Charles Stark of the Contra Costa County Fire Protection District told KRON4 on Aug. 1 that "due to the weather conditions, the high heat, crews got spent pretty quickly."

On Friday, July 31, a two-alarm vegetation fire burned roughly half an acre in the Oakland Hills near Joaquin Miller Park, drawing about 50 firefighters from Oakland, Cal Fire, Contra Costa County Fire, and East Bay Regional Park District.

What Lamorinda residents can do now

The Moraga-Orinda Fire District offers several free programs for residents in its service area:

• Vent mesh and gutter guards: Free wildfire-resistant materials for eligible Orinda residents to block embers. Details at cityoforinda.gov/701.
• Chipper program: MOFD will chip vegetation cleared from defensible space zones.
• Home assessments: The Community Wildfire Safety Ambassador program provides free 45-minute exterior fire-safety assessments for homes in Moraga, Orinda, Bollinger, and Canyon. Sign up at moragaorindafirewisenetwork.org.

MOFD can be reached at (925) 258-4599 or [email protected] during business hours, Monday through Friday, 8 a.m. to 5 p.m.

Sign up for emergency alerts

Contra Costa County's Community Warning System sends voice, text, and email notifications during emergencies. Residents can register at cococws.us.

The NWS had flagged rising heat and fire danger the previous week; this advisory represents a more severe event, with the offshore wind component adding fuel to already-dry vegetation across the East Bay hills. The Bay Area Air Quality Management District expects good to moderate air quality through the week despite wildfires burning in Mendocino, Sonoma, and Santa Clara counties.