Hilo, Hawaii 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

295
FXHW60 PHFO 270153
AFDHFO

Area Forecast Discussion
National Weather Service Honolulu HI
353 PM HST Sat Jul 26 2025

.SYNOPSIS...
A weak surface trough will move through the state the next few
days and will bring an increase of clouds and scattered showers
on Sunday. With the lack of breezy trades and an increase of
humidities, temperatures will feel warmer than usual through at
least Monday. Expect trades to strengthen to breezy levels around
the middle of next week.

&&

.DISCUSSION...
A weak surface trough will slowly move through the state the next
few days and will bring an increase of moisture. CIMMS MIMIC
precipitable water show values of 1.6-1.8 inches just east of the
Big Island this afternoon and the latest Hilo sounding is showing
a value of 1.55 inches. As this plume of moisture continues to
increase over the Big Island this evening and tonight, we should
see an increase of rain mainly over windward Big Island tonight.
Stable conditions aloft, should keep rainfall intensities at
moderate levels and if anything the rainfall should be beneficial
to our ongoing drought conditions.

For Sunday, we should see the trough continue to drift westward
and will likely bring an increase of moisture to the rest of the
state. With the lighter trade winds in place, localized sea
breezes should develop across select leeward areas by mid day. Sea
breeze convergence should lead to an increase of clouds and
scattered showers Sunday afternoon across interior and leeward
areas. For areas that do not see any shower activity, with the
increase in humidities, temperatures will feel muggy.

There is good model agreement with high pressure building back in
to the northeast of the state early next week, which should allow
the trade winds to strengthen back to moderate to locally breezy
levels by midweek. At the same time, a drier airmass is expected
to return to the islands.

We are continuing to monitor the development of Invest 90C far
southeast of the state. Central Pacific Hurricane Center has
increased the probability of development and now has a high chance
of cyclone formation during the next 7 days. Even if a tropical
cyclone were to develop, there is good agreement within the global
ensemble members for it to stay south of the Hawaiian Islands.


&&

.AVIATION...
A surface trough just east of the Big Island will begin to move
through the state tonight, which will bring an increase of
showers over windward Big Island and windward Maui. Trade winds
will weaken a notch tonight into Sunday with gentle to moderate
trade winds expected through Sunday.

Predominately VFR conditions are expected to prevail, however periods
of MVFR conditions will be possible especially over PHTO tonight
as showers increase.

There are currently no AIRMETs in effect, but an AIRMET for
mountain obscurations will be possible tonight into Sunday as
showers increase over windward areas of the Big Island and Maui.



&&

.MARINE...
A weak trough just to the east of the islands will transit
through the area through the rest of the weekend then dissipate
early next week as high pressure north of the area strengthens.
Trade winds will stay gentle to locally fresh through Monday due
to the trough, then strengthen Tuesday to moderate to locally
strong levels with the strengthening high pressure. There is also
potential for a tropical disturbance to track south of the waters,
this could influence the trade winds speeds.

South facing shores will remain small through the weekend with
mainly medium period background energy. A storm force low east of
New Zealand has produced seas up to 40 feet per JSON satellite
observations, likely impacting the islands during the second half
of next week. Confidence has increased that this low will generate
a moderate to large long period south swell that may approach or
exceed the High Surf Advisory threshold as it peaks.

East facing shores will gradually decline this weekend as trade
winds weaken locally and upstream of the state. East shores should
then increase next week as trade wind speeds increase. Flat to
tiny surf expected along north facing shores through the week.

&&

.FIRE WEATHER...
An increase of humidities are expected over the next few days as a
weak surface trough passes through the state. Trade winds are
also expected to decrease on Sunday with localized sea breezes
developing during the late morning through the afternoon hours.
Trade winds are expected to restrengthen Tuesday into Wednesday,
with developing dry conditions returning across the state. This
could bring elevated fire weather concerns during the second half
of next week.


&&

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

&&

$$


DISCUSSION...Kino
AVIATION...Kino
MARINE...Tsamous
FIRE WEATHER...Kino