Mendocino, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

687
FXUS66 KEKA 050729
AFDEKA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
1229 AM PDT Sun Jul 5 2026

.KEY MESSAGES...
* Seasonable temperatures along the coast with persistent overnight
  and morning marine stratus and fog.
* Warm conditions across the interior valleys through the weekend,
  with a 60-70% probability of a stronger warming trend mid-to-late
  next week.
* A 10% chance of afternoon thunderstorms over northeastern Trinity
  County on Monday.


&&

.SYNOPSIS...A shallow marine layer will continue to support night
and morning low clouds, fog, and seasonal temperatures near the
coast. Inland areas will see warm afternoon temperatures over the
weekend and early next week before a building high pressure ridge
brings hotter conditions to the interior valleys by mid-week.


&&

.DISCUSSION...An upper-level trough shifting past the Pacific
Northwest will maintain a persistent marine layer depth across
coastal sectors, yielding regular diurnal cycles of LIFR/IFR stratus
and localized beach fog. Inland, a building four corners high
pressure ridge will suppress deep mixing but sustain seasonably hot
temperatures, with valley highs reaching into the 90s to near 100
degrees in topographically favored hot spots like Big Bar.

As the upper trough approaches the Pacific Northwest coast on
Monday, it will draw a narrow corridor of mid-level moisture
northward from tropical system Douglas off Baja California. Weak mid-
level lapse rates and limited instability will keep thunderstorm
potential highly isolated and locked primarily east of our area,
though a 10% chance for an afternoon lightning strike remains
warranted across northeastern Trinity County near Trinity Lake. By
Wednesday and Thursday, the upstream trough weakens, allowing the
interior heat dome to build westward. This transition will initiate
a more robust warming trend, pushing daytime valley temperatures
deeper into the high 90s and low 100s for late next week.


&&

.AVIATION...The marine boundary layer remains highly stratified
tonight. Coastal terminals KACV and KCEC will experience persistent
IFR to LIFR flight categories due to low stratus ceilings and
developing mist/fog. Southerly or variable low-level winds returning
after midnight will further lock in the marine moisture, suppressing
visibility down to 1/2SM to 1 1/2SM at times through 15Z Sunday
before gradual diurnal lifting occurs. Inland, VFR conditions will
prevail at KUKI with light diurnal wind shifts and clear skies,
interrupted only by sparse high clouds.


&&

.MARINE...Northerly winds over the inner coastal waters will stay
light at under 10 knots as a thermal trough anchors over the
interior and encourages localized nocturnal wind veering.
Consequently, Small Craft Advisories remain strictly confined to the
outer waters from 10 to 60 nautical miles out. The localized
pressure gradient will compress slightly through Sunday morning,
generating brief periods of near-gale northerly gusts across the
northern outer waters zone. By Monday, an approaching Pacific
Northwest trough will weaken the inland thermal gradient, relaxing
the marine wind field and allowing hazardous small craft conditions
to drop off across the outer zones early next week.


&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...
None.
NORTHWEST CALIFORNIA COASTAL WATERS...
     Small Craft Advisory until 9 PM PDT this evening for PZZ470-
     475.

&&

$$

NOTE: The full forecast discussion is now regularly issued between
10 am/pm and 1 pm/am. Additional updates will be issued as needed.

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For forecast zone information
see the forecast zone map online:
https://www.weather.gov/images/eka/zonemap.png