High Surf in Hawaii, August 9 to 11, 2025

Area Forecast Discussion
National Weather Service Honolulu HI
301 PM HST Fri Aug 8 2025

.SYNOPSIS...
Trades diminish by Saturday afternoon resulting in a return of
hot and humid conditions as humidity gradually creeps up through
the weekend. Moderate trades return by the middle of next week.

&&

.DISCUSSION...

Locally breezy trades are poised to diminish as quickly as they
returned as Henriette passes north of the islands and wipes out
the local pressure gradient as early as Saturday afternoon. A land
and sea breeze pattern is then favored through at least Monday.
Hot and humid conditions gradually return during this time,
particularly as low level winds veer to SE in response to
developing upper troughing and advect dewpoints in the 70s back
into the area early next week. Gradual weakening of the inversion
as this occurs will favor increasing odds for afternoon clouds and
showers over island interiors, especially by Monday when low-
level moisture will be maximized and stability at a relative
minimum. Henriette advances north of 30N by Tuesday relinquishing
the islands from any of its effects, but a general pattern of mid-
level height falls over the central and east Pacific continue
well into next week which will generally keep trades moderate as
stable weather returns for remainder of the forecast period.

&&

.AVIATION...

Breezy trades continue through the near term then gradually
diminish during Saturday as a tropical system passing north of the
islands wipes out the local pressure gradient. Limited clouds and
showers windward and mauka will produce patchy MVFR but VFR is
forecast to prevail.

AIRMET Tango for lee turb will be allowed to expire this evening.

&&

.MARINE...

Moderate to locally strong trade winds will decrease tonight
through tomorrow as Post Tropical Cyclone Henriette approaches
the area and passes northeast of the offshore waters. Winds will
become light and variable tomorrow through Monday morning due to
the weakening ridge from Henriette. Then as Henriette exits the
region to the north, the ridge will build back in by Monday
afternoon through the remainder of next week, increasing trade
winds into the fresh range by Tuesday. Global models indicate a
trough approaching the area and weakening the winds again by the
later part of next week.

Elevated surf heights can be observed today across the south
facing shores. This is from a swell that arrived earlier today
and will continue supporting advisory level surf before another
reinforcing pulse arrives tonight into tomorrow. Surf heights are
expected to border on warning levels later tonight and hold
through tomorrow. A High Surf Advisory for all south-facing shores
is in effect through Sunday night and could be upgraded to a
warning if the swell comes in larger. The swell will gradually
fade through next week.

Surf for east facing shores should remain choppy tonight and
should decrease slightly tomorrow as trade winds decrease. A
medium period east swell from Tropical Storm Henriette may arrive
around Sunday and briefly increase the east facing shores.

A small, medium northwest swell passing through today and tomorrow
will keep north shore surf from going completely flat. Another
tiny northwest swell is expected to arrive by Monday.

Peak afternoon high tides, combined with elevated water levels
running about a half a foot higher than predicted and a large
south swell, will lead to minor flooding along many south-facing
shorelines and low lying coastal areas through Sunday afternoon.

&&

.FIRE WEATHER...
Breezy trades gradually diminish through Saturday with light
winds then continuing into next week. After bottoming out in the
upper 60s today, dewpoints will gradually rise back into the 70s
for Sunday and Monday. Minimal fire weather concerns during this
time.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
High Surf Advisory until 6 AM HST Monday for Niihau-Kauai
Leeward-Waianae Coast-Kahoolawe-Maui Leeward West-Kona-Kohala-
Kauai South-East Honolulu-Honolulu Metro-Ewa Plain-Molokai
Southeast-Molokai Leeward South-Lanai Leeward-Lanai South-Maui
Central Valley South-South Maui/Upcountry-South Haleakala-Big
Island South-Big Island Southeast.

&&

DISCUSSION...JVC
AVIATION...JVC
MARINE...Tsamous
FIRE WEATHER...JVC