Excessive Heat in California, June 26 to 29, 2021

Name: Excessive Heat in California, June 26 to 29, 2021
Start: 2021-06-26T12:00
End: 2021-06-29T20:00
Location: California

June 26 to 29, 2021 · NWS STO · 5 events in 5 counties and zones

High pressure centered over the Pacific Northwest brought record high temperatures over the weekend. The heatwave was widespread across the Northwestern United Sates.

The toll

Deaths: 0
Injuries: 0
Property damage: None recorded
Crop damage: None recorded
Events: 5

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.

What happened

The episode as NWS STO wrote it up.

High pressure centered over the Pacific Northwest brought record high temperatures over the weekend. The heatwave was widespread across the Northwestern United Sates. The Northern Sacramento Valley saw high temperatures reach in excess of 110 degrees over the weekend. Well above normal temperatures in the central and northern Sacramento Valley brought very high heat risk to the area. Several daily high temperature records were broken in the Northern Sacramento Valley on the Saturday the 26th. During the event, two cooling centers were made available to the public in Shasta County.

What forecasters said that day

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 Sacramento, CA wrote its last area forecast discussion before the first event at Jun 26, 2:30 AM PST, 9 hours 30 minutes earlier.

Area forecast discussion, Jun 26, 2:30 AM PST, 9 hours 30 minutes before

Area Forecast Discussion
National Weather Service Sacramento CA
330 AM PDT Sat Jun 26 2021

.SYNOPSIS...
High pressure strengthens this weekend resulting in hot weather
into next week, particularly for the northern half of the
Sacramento Valley.

&&

.DISCUSSION...
Clear skies cover the region early this morning. The marine layer
has decreased in depth, but IR difference imagery shows stratus
extending through much of the Bay Area. A moderately strong Delta
Breeze is continuing to usher cooler air into the southern
Sacramento and northern San Joaquin Valleys where current
temperatures range from the mid 50s to mid 60s. Elsewhere current
temperatures are mainly in the 60s and 70s, a little warmer
compared to 24 hours ago.

NorCal will remain on the periphery of strong high pressure
centered over the PacNW through early next week. Water vapor
imagery shows subsidence associated with the high over Oregon and
Washington, and plenty of subsidence further south over NorCal
too. The subsidence and strong mid-level cap will limit cumulus
development over the mountains today and Sunday.

Heat peaks across the northern half of the Sacramento Valley over
the weekend when warmest temperatures will likely exceed 110
degrees in Redding and Red Bluff with overnight lows in the 70s to
lower 80s resulting in high to very high heat risk into early next
week.

Further south, enough onshore flow will cap temperatures around
the century mark, or slightly above, in the Sacramento region
today with just a few degrees of cooling expected into early next
week.

&&

.EXTENDED DISCUSSION (Wednesday THROUGH Saturday)...
Upper high over the Intermountain West is main synoptic feature
through the extended forecast period. This will continue above
normal daytime temperatures with widespread triple digit heat in
the Northern and Central Sacramento Valley. Models suggest
anticyclonic flow around upper high could advect some moisture
over the Sierra Nevada leading to potential for deep moist
convection resulting in possible afternoon showers or
thunderstorms over higher terrain.

&&

.AVIATION...
VFR conds ovr intr NorCal nxt 24 hrs exc isold MVFR conds poss
ovr Siernev in shwrs/tstms btwn 20-03z. Lcl MVFR/IFR poss vcnty of
Delta in ST til abt 19z. SWly sfc wnd 25g35kt poss vcnty of Delta
at times.

&&

.STO WATCHES/WARNINGS/ADVISORIES...
Excessive Heat Warning from noon today to 10 PM PDT Wednesday
for Burney Basin / Eastern Shasta County-Central Sacramento
Valley-Mountains Southwestern Shasta County to Western Colusa
County-Northeast Foothills/Sacramento Valley-Northern Sacramento
Valley-Shasta Lake Area / Northern Shasta County-Southern
Sacramento Valley.

&&

Event by event

5 excessive heat. Local standard time, as filed.

Excessive Heat, Shasta Lake/North Shasta County

When: June 26, 12:00 PM PST to June 29, 8:00 PM PST
Where: Shasta Lake/North Shasta County forecast zone
Reported by: ASOS

Lake Shasta Dam saw high temperatures reach 108 to 109 degrees over the weekend.

Excessive Heat, Northern Sacramento Valley

When: June 26, 12:00 PM PST to June 29, 8:00 PM PST
Where: Northern Sacramento Valley forecast zone
Reported by: ASOS

On June 26th, Redding and Red Bluff broke daily high temperature records of 114 and 115 degrees respectively.

Excessive Heat, Central Sacramento Valley

When: June 26, 12:00 PM PST to June 29, 8:00 PM PST
Where: Central Sacramento Valley forecast zone
Reported by: ASOS

The Central Sacramento Valley region saw high temperatures reach in excess of 110 degrees during the event.

Excessive Heat, Mountains Southwestern Shasta County to Western Colusa County

When: June 26, 12:00 PM PST to June 29, 8:00 PM PST
Where: Mountains Southwestern Shasta County to Western Colusa County forecast zone
Reported by: ASOS

The western foothills of the Sacramento Valley saw high temperatures reach upwards of 105 to 107 degrees over the weekend with warm overnight lows.

Excessive Heat, Northeast Foothills/Sacramento Valley

When: June 26, 12:00 PM PST to June 29, 8:00 PM PST
Where: Northeast Foothills/Sacramento Valley forecast zone
Reported by: ASOS

The north eastern foothills of the Sacramento Valley saw high temperatures reach in excess of 110 degrees with warm overnight lows.

What these are

Excessive Heat: Heat at or above the local excessive heat warning criteria, or heat that caused deaths.

After NWS Directive 10-1605, the rules offices file Storm Data by.

The same day elsewhere

Every storm in California in 2021 Every state in 2021 This day in weather history Warnings in California, June 2021

Sources

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: 970010, 970011, 970013, 970014, 970015.