Mililani Mauka, Hawaii 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

999
FXHW60 PHFO 251338 CCA
AFDHFO

Area Forecast Discussion...CORRECTED
National Weather Service Honolulu HI
338 AM HST Sat Apr 25 2026

.SYNOPSIS...
Trades will continue through the next several days, gradually
increasing in speed by mid-week next week, maintaining typical
windward and mauka showers. A weak upper-level disturbance
approaches the islands early next week, resulting in a possible
uptick in moisture across windward slopes. This will be short-
lived, however, and steady trades will return again for the
remainder of the forecast period.

&&

.DISCUSSION...
Latest radar imagery continues to display isolated windward showers
riding on a prolonged trade wind pattern under a high pressure
system anchored to the north of the Hawaiian Islands. Moderate to
locally breezy trades will veer slightly from the northeast to a
more easterly pattern this morning, gradually increasing in speed by
mid-week, and then persisting through the remainder of the
forecast period. This will help maintain typical trade showers
across windward and mauka areas, though any precipitation
associated with these showers is expected to remain light.

Global model guidance preserves the likeliness of a weak upper-
level disturbance shifting over the islands as early as Monday,
effectively increasing the moisture content across the windward
slopes of most islands. This uptick in moisture may lead to some
stronger showers due to instability from colder air aloft. Model
precipitable water (PWAT) normalized anomalies show an increase
from near normal to 1 to 2 standard deviations above normal from
Monday to Wednesday, falling back to near normal. Trades will re-
establish shortly thereafter, prevailing through the remainder of
the week.

&&

.AVIATION...
A high pressure system far north of the Hawaiian Islands will keep
moderate to locally breezy easterly trade winds in the forecast
through Sunday. An upper level disturbance will produce bands of
showers riding into windward island mountains on the trade winds,
expect periods of showers mainly over windward mountain areas
favoring the overnight to early morning hours. Periods of MVFR
conditions are expected through Sunday along windward mountain
slopes due to low clouds and showers.

AIRMET Sierra in effect for mountain obscurations along north and
east slopes of the Big Island of Hawaii. This AIRMET may need to
expand in coverage to other islands later this morning.

&&

.MARINE...
A ridge of high pressure far north of the state will maintain
moderate to breezy trade winds through today. A slight decrease
is expected tonight into early next week as a weak trough passes
through the state. The trough should bring an increase of shower
coverage especially over windward waters. High pressure will
rebuild far north of the state towards the middle of next week,
which should bring the return of moderate to locally strong
trades.

A small medium period NW swell continues to fill in this morning
and will be reinforced by a larger NW swell filling in tonight.
This reinforcing NW swell should peak on Sunday, then gradually
decline through early next week. A developing hurricane-force low
this weekend near the Aleutian Islands should send a moderate
northwest swell towards the middle of next week.

Local nearshore buoys such as the Mokapu buoy is showing a modest
increase of short-period energy from the NE this morning
associated with a small fetch of strong winds few hundred miles NE
of the state the past few days. This should provide a short-lived
increase along east facing shores through this morning then
gradually decline into Sunday. Otherwise, below average surf is
expected along eastern exposures into next week due to the lack of
any strong trade wind activity over and upstream of the state.
Locally strong trade winds could return during the second half of
next week, which could bring rough and choppy surf with near
normal wave heights by the later half of next week.

Small background energy from the west will continue to linger through
today and fade out on Sunday. A small southwest bump from the
Tasman Sea that passed across the American Samoa 51209 buoy
Wednesday is expected to slowly fill in today and peak on Sunday.
No significant south swell is expected through the first half of
next week. A fetch of gales passing east of New Zealand today
could produce a small south-southwest swell for next weekend.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$

DISCUSSION...Pierce
AVIATION...Bohlin
MARINE...Kino