Diamond Head Beach Park, Hawaii Weather Forecast Discussion

883
FXHW60 PHFO 290116
AFDHFO
Area Forecast Discussion
National Weather Service Honolulu HI
316 PM HST Sun Sep 28 2025
.SYNOPSIS...
Moderate to locally breezy trade winds will keep the majority of
showers windward and mauka during the next couple of days.
Afternoon showers will develop over leeward slopes of the Big
Island, but most other leeward areas will be dry. Showers may
increase slightly Wednesday in most areas. Trades will decrease
slightly midweek and may further decline Friday.
&&
.DISCUSSION...
Stable, moderate to locally breezy trade winds have become
established over the island chain. The trades are being driven by
robust surface high pressure centered roughly 1,000 miles north
of Kauai. A compact upper-level low continues to produce
thunderstorms northwest and southwest of the Kauai coastal waters,
but stable conditions dominate over the islands as an upper-level
ridge building in from the east has pushed the inversion down to
between 6,000 to 7,000 ft. The locally breezy and stable trade
wind flow has produced modest rainfall over windward slopes today,
just a few hundredths of an inch at most gages. While leeward
areas have remained dry on most islands, spotty afternoon showers
have developed along the Kona slopes of the Big Island. For
tonight, expect showers to diminish over leeward Big Island, while
windward Oahu and Kauai experience a slight uptick in shower
activity.
Moderate to locally breezy trade winds and stable conditions will
prevail through much of the work week. A band of moisture is
expected to provide a boost in shower activity, mainly windward,
Tuesday night and Wednesday. The surface high to the north will
begin to weaken during this time, likely leading to a very gradual
easing of the trade winds.
Guidance continues to be a bit inconsistent, but the trend favors
trades dropping into light to moderate strength Friday and
Saturday.
&&
.AVIATION...
Moderate to locally breezy trades will continue to deliver
limited clouds and showers, mainly over windward and mauka areas.
A slightly greater coverage of showers is expected over windward
Big Island as upstream moisture moves ashore Monday morning.
Localized MVFR possible within passing showers, but VFR will
prevail.
No AIRMETs in effect nor expected through the forecast period.
&&
.MARINE...
Moderate to locally fresh easterly trade winds will continue to
build into the area through Monday. Wind observations and a
morning scatterometer pass showed that Small Craft Advisory (SCA)
conditions are likely occurring in the typically windy waters
around the Big Island and Maui County. A SCA for these areas
remains in effect through Monday afternoon. Winds weaken slightly
late Monday, but moderate to locally fresh trade winds continue
through much of the week.
A small medium-period northwest swell will continue to fade
tonight. A series of small medium-period swells from the north
and northwest will trickle in through the middle of the week. A
moderate long-period northwest (330 deg) swell will overlap with
a smaller medium-period north swell by Saturday resulting in
building surf along north facing shores this upcoming weekend.
Surf along south facing shores will start to subside tonight into
Monday as energy fades from a small medium-period south swell. A
series of small medium-period south swells will keep surf along
south facing shores from going flat through the week.
Surf along east facing shores will remain on the small side as
trade winds return.
&&
.FIRE WEATHER...
Locally breezy trade winds and rather dry conditions will persist
into Tuesday, but conditions should remain just below critical
fire weather thresholds. A brief period of wetter trade wind
weather is expected on Wednesday, followed by decreasing winds
later in the week. A strengthening inversion will build down to
5,000 to 6,000 feet on Monday.
&&
.HFO WATCHES/WARNINGS/ADVISORIES...
Small Craft Advisory until 6 PM HST Monday for Maalaea Bay-
Pailolo Channel-Alenuihaha Channel-Big Island Leeward Waters-Big
Island Southeast Waters.
&&
$$
DISCUSSION...Wroe
AVIATION...TS
MARINE...Ahue
FIRE WEATHER...Wroe

NWS HFO Office Area Forecast Discussion