After the hottest weekend so far this year, cooler weather is on the horizon for July 4th. Temperatures in the Bay Area are expected to remain above normal on Monday and return to seasonal normals for the bank holiday on Tuesday.
Afternoon onshore breezes will increase throughout the week bringing relief to Livermore and Concord, which have seen highs in the 100s this weekend. The sea layer will deepen and expand as the week progresses, with extensive clouds and below-average temperatures expected through Friday.
The heat escapes to the east
The European weather model is forecasting a cooldown in the Bay Area on Monday, with temperatures 5 to 15 degrees lower than this weekend. The high-pressure system responsible for the warm weekend will move east across the Four Corners region.
weather bell
The searing high-pressure system that brought record daily temperatures to parts of the Bay Area this weekend is on its way out, moving east. Although high pressure will persist near the Central Valley, sea breezes and periods of fog are expected to return in the Bay Area.
San Francisco’s high on Tuesday is expected to be near the seasonal normal of 67.
People planning to vacation elsewhere in California should prepare for hot weather. Palm Springs is forecast to remain in the low 110s and the Sacramento Valley will continue to hover in the 90s and 100s.
fireworks forecast
The North American model is forecasting reduced visibility along the Pacific Coast and parts of San Francisco Tuesday evening, obscuring the July 4th fireworks display.
Crucial Weather
San Franciscans hoping for fog-free fireworks will likely be disappointed Tuesday night. As the holiday season begins, the fog layer thickens, reaching the top of the Twin Peaks by Monday evening and encroaching into the Oakland hills by the morning of July 4th.
Fog will likely spoil the fun at Tuesday’s 9:30 p.m. show in front of San Francisco’s Pier 39. Clouds are expected to move west of Sutro Tower again later in the day, but clouds are expected to cover the Golden Gate Bridge by early evening.
Fireworks fans heading to Crissy Field Tuesday night should pack a warm sweatshirt and windbreaker. Temperatures around 50°C with gusts of up to 40 km/h and plenty of fog are expected.
Elsewhere in the Bay Area, conditions for fireworks are expected to be more comfortable. Evening breezes and temperatures around 60°C should prevail from Santa Rosa to San Jose with mostly clear skies.
July without sky?
According to the American weather model, cooler weather is on the way in California. By Friday morning, the sea layer will be several thousand feet thick and could extend inland.
weather bell
The start of the next weekend is becoming apparent and stands in stark contrast to the hot start to July. Weather models suggest much cooler weather will return to Northern California due to a low pressure system.
Strong onshore breezes will bring fog and drizzle to parts of the Bay Area Thursday and Friday morning. Even the high sun in July probably won’t be strong enough to burn through the low cloud layer, leaving parts of Marin, San Francisco and San Mateo counties in fog all day.
Temperatures around 50°C along the coast and 70°C inland are expected on Thursday and Friday.
collapse on Monday
San Francisco: Familiar fog is expected to return to Richmond and Sunset counties this morning. The fog will be flat, allowing any clouds advancing east of Sutro Tower to burn away by the afternoon.
Highs are expected to be in the mid 50’s on the West Side and in the mid 60’s in Downtown, South Market and the Mission. Afternoon and evening breezes reach speeds of up to 25 miles per hour, driving the fog over Twin Peaks and into the city overnight. Lows will be in the low to mid 50’s.
Pacific Coast and Peninsula: Bay Area residents and tourists planning to spend their long weekend on the coast should expect plenty of fog and cool weather.
The fog layer is expected to be more extensive than Sunday, meaning high temperatures in Pacifica, El Granada and Half Moon Bay will drop a few degrees into the upper 50s and low 60s. Fog is not expected to penetrate into the Highway 101 corridor, but high temperatures will also drop by about 5 degrees. Daly City will be in the low 60’s, San Mateo around 80 and Redwood City in the low 80’s.
Evening breezes will bring another wisp of fog east of the Coastline. Lows will be in the low to mid 50’s.
North Bay: The National Weather Service has discontinued its heat alerts and warnings for the region, but temperatures will remain above normal in many places on Monday.
Marin County will see the greatest relief from the heat, with temperatures in Sausalito and Mill Valley in the mid to high 60s. A flat ocean layer means temperatures will be higher at higher elevations, with Mount Tamalpais expected to warm into the 80s.
Temperatures will be more comfortable in Santa Rosa, Petaluma, and Napa, where highs reach lows well into the mid-80s. The Tri-Valley should avoid the triple digits, with low to mid 90s expected. Overnight temperatures will drop to the mid-50s, with patchy fog invading the Santa Rosa, Petaluma and Napa Valleys.
east bay: An end to the heatwave is on the way. A stronger bay breeze will drive some morning clouds to Oakland and Berkeley, lowering highs to the upper 60s to mid 70s with Fremont dropping to the low 80s. Weekend hot spots like Livermore and Concord will cool to 5 to 10 degrees into the low to mid 90s.
Afternoon breezes will blow at speeds in excess of 20 miles per hour and drive fog toward the Oakland hills Tuesday morning. The lows will be much lower than over the weekend, dropping into the mid-50s.
South Bay and Santa Cruz: Although temperatures will remain high around the Santa Clara Valley, a 5 degree drop is expected on Monday. Highs will be in the mid to high 80’s in Santa Clara, San Jose and Cupertino.
A southerly wind will drive the fog from Monterey Bay into Santa Cruz Monday morning. Due to the flat sea layer, temperatures will in turn be higher at higher altitudes. Highs are in the mid-60s near the water and lows in the mid-80s in Scotts Valley and Boulder Creek.
Reach Anthony Edwards: anthony.edwards@sfchronicle.com
