Over the next few days, a series of significant heatwaves could occur in Northern California, setting off a chain of events that could cause temperatures in the deserts of southwestern United States to rise into the triple digits.
What about the coast?
Weather models paint an uncertain picture of how the hot weather will impact the San Francisco Bay and Pacific coast by Thursday.
According to Miller, “Our position along the northwest periphery experiences a bit more vulnerability to cooling influences as the flow moves onshore, leaving the coastal areas with still relatively high upper leaves.”
Thanks to a slight wobble in the high-pressure system, cities such as San Francisco and Oakland are expected to experience daytime temperatures in the 70s instead of reaching the upper 80s this week. The cool Pacific winds are effectively protecting the coast and the bay from the worst of the heat.
As we approach the heat event, Wonks Weather will monitor this developing story closely, as uncertainties with the setup of weather in all involved parts become forecasted on Friday.
Makings of a heat wave
An area of high pressure over northern Mexico will begin to draw excessive heat from the Sonoran Desert into California starting Monday.
The remaining days of the week, extending as far north as Redding, will witness temperatures soaring into the 100s in cities like Bakersfield and Fresno, gradually infiltrating the San Joaquin Valley by Tuesday. This scorching desert air will persist thereafter.
During this early stage of summer, it is uncommon to experience extended periods, but it is not unheard of to have temperatures reaching triple digits in Northern California in July.
Sean Miller, a chief meteorologist at National Weather Service Bay Area and Monterey, penned, “There is a higher level of certainty regarding scorching temperatures for the mountains and inland valleys, and the overall conditions resemble those typically seen in September.”
A timeline of potential impacts
Based on guidance from both the National Weather Service and weather models, it appears that there will be a long stretch of hotter weather in the Bay Area on Wednesday and in the Sacramento Valley on Tuesday.
Simulations on both the European and American weather models indicate that temperatures in Northern California are surpassing the average for this time of year by 5 to 7 degrees. Stockton and Sacramento could experience high temperatures exceeding 100 degrees by Wednesday, whereas a pleasant 70 degrees will be felt in San Francisco.
According to NWS Sacramento lead meteorologist Eric Kurth, Kurth stated, “We are anticipating a shift towards moderate heat risk on Tuesday and Wednesday.” This implies that the high pressure system has a high likelihood of causing prolonged periods of extreme heat. Eric Kurth expects a pattern of high pressure building over Northern California by the middle of the week.
The European weather model predicts that the ridge of high pressure — shaded in warm, red hues — will expand its reach into the L.A. Basin, Central Valley and parts of the Bay Area as early as Tuesday.
WeatherbellStarting Tuesday afternoon, there is a possibility that some of the moderate heat risk may extend into the inland valleys of the Bay Area. As shown on the graphic above, the region will gradually become congested with hot air, which will be colored in warm, red shades, resembling the fumes emitted by vehicles on a bustling freeway.
By Thursday, the likelihood of temperatures in the upper 90s to lower 100s will increase, intensifying over the inland valleys of the Bay Area, as the continual influx of warmth from the high-pressure system will then amplify over the inland cities such as Livermore, Santa Rosa, and Dublin between Tuesday and Wednesday, suggesting that daytime temperatures could effortlessly reach the lower to mid-90s according to both the European and American models.
Miller stated, “The extent seems to be comparable, if not larger, than the heat occurrence last weekend.” “This will result in rising temperatures and the possibility of extreme heat, especially for inland regions.”
Residents who plan to be outside for long periods of time, especially between the hours of 5 PM and 11 AM, should consider making trips to seek shade or cooling shelters as the hot weather can be a nuisance and raise concerns about heat-related illnesses. Additionally, this prolonged heat also raises concerns about populations vulnerable to risk.
Saturday breakdown
This morning in San Francisco, it will be difficult to find sunshine. The weather will be cool and humid, with patches of fog and a chance of drizzle continuing on the west side until 1 p.M. However, residents of San Francisco east of Sutro Tower can anticipate partly sunny skies by 11 a.M.
On the western side, daytime temperatures will range in the lower 60s, whereas in other areas they will be in the mid-60s. Occasional clouds will cause temperatures to remain slightly below the average for this time of year, by about 1 to 3 degrees.
This evening, near the shoreline, the Golden Gate Bridge and slopes, maritime mist will once again return. Expect temperatures dropping to the lower to mid-50s during the night.
In the 1960s, cities such as Richmond, Hayward, and Alameda will experience cooler air from the west due to the Caldecott Tunnel, keeping temperatures closer to the upper 60s. Meanwhile, Pleasanton and Dublin, located in Walnut Creek, have a good chance of reaching the mid-70s for daytime highs. By noon, the Tri-Valley area will gradually see the return of sunshine, while the hills of Berkeley and Oakland are likely to have fog from the East Bay.
Look for a cool and humid evening with a bay breeze gusting up to 20 mph, bringing marine clouds to the shore. Temperatures will be in the upper 50s to mid-50s for nighttime, starting after 7 p.M.
Most of Country Wine will see partly cloudy skies and breezy afternoons with temperatures in the mid-70s. Although there might be some clouds hanging around in the highlands, residents of Petaluma, Santa Rosa, and Napa can expect a quick return to sunshine after 9 a.M. The residents of North Bay might miss some of this morning’s fog.
The temperatures around Bay Bodega and Reyes Point will be chillier in the afternoon, closer to 60 degrees. The same goes for the cities along the Marin County coast, where Tiburon and Sausalito can expect upper 60s. However, inland cities like San Rafael and Novato can expect lower 70s as the sunny skies raise the highs and bring a burst of warmth.
Ocean clouds will come back to the bay coastline and inland valleys tonight. Seek for nighttime temperatures in the mid-50s.
Expect much higher fog in the afternoon than in the sunny morning skies on the Peninsula. Although there may be a few breaks of sunshine in the afternoon, fog, drizzle, and clouds are likely to persist along Highway 1 for most of the day. This is applicable to the Peninsula and the Pacific Coast.
This afternoon, the temperatures in the mid-60s are expected to reach optimum levels in the “Goldilocks zone”, with residents of San Mateo, Millbrae, and South San Francisco situated in the San Bruno Gap experiencing a pleasant combination of cool and warm air. Along the I-280 and Highway 101 corridor, temperatures will rise to the lower 70s as the winds become lighter and the skies become sunnier. On the coast, in Daly City, Pacifica, and Miramar, the daytime highs will be around 60 degrees, accompanied by gusts of wind up to 30 mph.
After sunset, the Peninsula will be covered by marine clouds, which will maintain nighttime temperatures in the mid- to upper 50s.
The mid-70s are anticipated in downtown San Jose, as a gentle bay breeze arrives around 2 p.M. During the daytime, San Jose is expected to have temperatures in the lower 70s, while Felton, Scotts Valley, and Ben Lomond will experience temperatures near 70 degrees. Inland valleys and mountain communities, including South Bay and Santa Cruz, can expect sunshine to return after 11 a.M.
Fog will continue along the immediate shoreline until 1 p.M. Expect partly cloudy conditions along Highway 1 and temperatures in the lower 60s for cities such as Capitola, La Selva, and Aptos.
During the nighttime, temperatures in the mid-50s will decrease, causing humidity levels to rise once more. Inland areas will experience fog and marine clouds as they make their way over Monterey Bay.
Contact Gerry Díaz via email at gerry