A ridge of high pressure over the desert southwest brought warm and dry conditions across the Central Coast and Bay Area around the Fourth of July. A handful of wildfires that broke out that weekend were aided by breezy onshore winds towards the end of the weekend and into the start of the following week.
Every event with a place to put it; 2 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.
Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS MTR wrote it up.
A ridge of high pressure over the desert southwest brought warm and dry conditions across the Central Coast and Bay Area around the Fourth of July. A handful of wildfires that broke out that weekend were aided by breezy onshore winds towards the end of the weekend and into the start of the following week. Some of the fires prompted the issuance of evacuations across the region.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS San Francisco Bay Area, CA wrote its last area forecast discussion before the first event at Jul 4, 12:20 PM PST, 8 minutes earlier.
Area Forecast Discussion
National Weather Service San Francisco Bay Area
120 PM PDT Sat Jul 4 2020
.SYNOPSIS...High pressure will remain over the region through the
remainder of the weekend resulting warm and dry conditions.
Temperatures cool and the marine layer is likely to return as
onshore flow increases early next week.
&&
.DISCUSSION...as of 01:20 PM PDT Saturday...A region-wide warming
trend is well underway this afternoon with temperatures currently
a few to as much as 15 deg F warmer compared to 24 hours ago.
Additionally, clear sky conditions prevail as the warm, dry air
mass aloft has mixed well to the surface. Thus, look for
widespread 80s to lower 90s for most interior locations while mid
90s are possible in the region's warmest spots. Light onshore flow
near the coast will keep temperatures in the 60s to 70s there and
up to the lower 80s in places such as Santa Cruz.
The ridge of high pressure over the Desert Southwest bringing this
warm weather to the region will remain in place on Sunday. This
should allow for mostly clear conditions overnight with just an
outside chance for patchy fog near the coast and into the coastal
valleys early Sunday morning. Onshore winds do increase a bit by
Sunday afternoon and will keep temperatures near to slightly cooler
compared to today.
Temperatures cool early next week along with a likely return of our
typical summer time marine layer as an upper level trough digs into
the Pacific Northwest. Medium range guidance indicates a series of
short-wave disturbances rounding the base of the trough through the
upcoming week. Thus, look for temperatures to reamin near to
slightly below seasonal averages (especially inland) with periods of
night/morning coastal clouds spreading inland into the valleys each
night.
&&
.AVIATION...As of 10:31 AM PDT Saturday...For 18Z TAFs. VFR.
Recent models are trending toward stronger onshore wind gusts,
particularly for coastal terminals, breezier inland. A FEW clouds
passing overnight for the the Bay Area, but continued forecast of
IFR/LIFR conditions around the Monterey Bay with patchy fog
before clearing mid to late morning.
Vicinity of KSFO...VFR. W/NW will increase in the afternoon with
stronger gusts around 28 kts. Winds will remain breezy and onshore
through the evening.
SFO Bridge Approach...Similar to KSFO.
Monterey Bay Terminals...Low clouds have retreated to over the Bay
for the time being. Skies will be VFR with breezier onshore winds
in the afternoon, and an occasional stronger gust funneled through
the Salinas Valley. As winds ease overnight, low clouds are set to
return for IFR/LIFR conditions around the peninsula, with higher
confidence closer to the coast.
&&
.MARINE...as of 08:30 AM PDT Saturday...As surface high pressure
builds over the eastern Pacific, northwest winds will increase
across the coastal waters today and tonight. Moderate to strong
winds will prevail across the waters through the holiday weekend.
These winds will generate steep fresh swell resulting in hazardous
seas conditions, particularly for smaller vessels. A long-period
southerly swell train will persist through the weekend. This will
cause occasional breaking waves over nearshore shoals and strong
currents along the coast, especially near points and headlands.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
.Tngt...SCA...Pigeon Pt to Pt Pinos 0-10 nm
SCA...Pt Arena to Pt Reyes 0-10 nm
SCA...Pt Reyes to Pigeon Pt 0-10 nm
SCA...Pt Pinos to Pt Piedras Blancas 0-10 nm
SCA...Pt Arena to Pigeon Pt 10-60 nm
SCA...Pigeon Pt to Pt Piedras Blancas 10-60 nm
SCA...SF Bay until 9 PM
SCA...Mry Bay until 9 PM
&&
PUBLIC FORECAST: RGass
AVIATION: DK
MARINE: DK
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www.youtube.com/nwsbayareaThe national radar mosaic for the moment the first event began.
4 wildfire. Local standard time, as filed.
The Sheridan Fire broke out in dry brush in the hills of Alameda County. Breezy winds initially fueled the spread of the fire before it was contained https://www.fire.ca.gov/incidents/2020/7/4/sheridan-fire/.
The Park Fire broke out over Fourth of July weekend east of Morgan Hill prompting evacuations https://www.fire.ca.gov/incidents/2020/7/5/park-fire/.
Fueled by breezy winds the Crews Fire broke out east of Gilroy prompting evacuations across the area and destroying one structure https://www.fire.ca.gov/incidents/2020/7/5/crews-fire/. Smoke from the fire was also effecting the San Joaquin Valley.
The California Fire started in Contra Costa County near I-80. Part of Cummings Skyway near where the fire was burning was closed https://www.fire.ca.gov/incidents/2020/7/6/california-fire/. End time is approximate.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in California in 2020Every state in 2020This day in weather historyWarnings in California, July 2020
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 905852, 906066, 906069, 906079.