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870
FXCA62 TJSJ 261901
AFDSJU

Area Forecast Discussion
National Weather Service San Juan PR
301 PM AST Wed Aug 26 2026

...New SHORT TERM, LONG TERM, AVIATION, MARINE, BEACH FORECAST, FIRE WEATHER...

.KEY MESSAGES...
Updated at 226 PM AST Wed Aug 26 2026

* Warmer temperatures will continue across the islands, with an
  elevated to locally significant heat risks throughout the
  remainder of the week.

* As the drier airmass and Saharan dust layer move from the local
  area, showers and isolated thunderstorms are expected on
  Thursday afternoon, increasing the flooding and lightning
  threat.

* The potential for life- threatening rip currents will increase
  to moderate from this evening onward, especially along most
  exposed beaches of Puerto Rico and the US Virgin Islands.

* A weak tropical wave will move quickly across the region late
  Friday night into Saturday morning, increasing showers and
  thunderstorms, followed by brief drier conditions.

* The National Hurricane Center continues to monitor AL96, with a
  medium formation chance of development, though uncertainty
  remains high regarding impacts, if any, across the islands.

&&

.Short Term(This evening through Friday)...
Issued at 226 PM AST Wed Aug 26 2026

Hazy skies and generally fair weather conditions prevailed across
the islands during the morning hours as moderate concentrations of
Saharan dust remained across the region. Shower activity was
limited, with only a few passing showers noted over the local
waters. Meanwhile, warm temperatures combined with sufficient low-
level moisture will continue to result in elevated to locally
significant heat risks, particularly across urban and coastal areas.
Therefore, the Extreme Heat Warning and Heat Advisory remain in
effect through 5 PM AST.

For this afternoon, precipitable water values are expected to remain
near seasonal levels, generally between 1.6 and 1.7 inches. However,
relatively dry air in the mid-levels, consistent with the lingering
Saharan air layer, should limit the overall coverage of convection.
Nevertheless, sufficient low-level moisture combined with strong
daytime heating, sea-breeze convergence, and local effects will
support isolated to scattered showers, mainly across the interior
and western/southwestern portions of Puerto Rico. Locally heavy
rainfall could result in ponding of water on roads and in poorly
drained areas, with a limited flooding risk where the heaviest
rainfall occurs. Moderate Saharan dust concentrations will also
maintain hazy skies through this evening.

A gradual increase in moisture is expected tonight into Thursday as
a moisture surge moves across the region. Precipitable water values
will increase to around 1.8-1.9 inches, while low- to mid-level
relative humidity increases as the Saharan air layer gradually
erodes. Therefore, passing showers are expected to increase across
the local waters and windward portions of the islands during the
overnight and morning hours. By Thursday afternoon, the combination
of deeper moisture, daytime heating, and local effects could favor a
round of showers and thunderstorms across the interior and western
portions of Puerto Rico. Although lapse rates aloft are expected to
become somewhat less favorable, the deeper moisture profile should
support locally heavy rainfall with the strongest activity. A
limited to elevated flooding risk will persist, but widespread
flooding is not anticipated.

A noticeable drying trend is then expected Thursday night into
Friday as increasing subsidence develops ahead of this weekend`s
tropical wave. Model guidance indicates precipitable water values
falling below seasonal levels, accompanied by a pronounced decrease
in low- and mid-level relative humidity and more stable conditions
aloft. These conditions should limit shower and thunderstorm
activity through much of Friday. Nevertheless, sufficient low-level
moisture, daytime heating, and local effects may still support
isolated afternoon convection, mostly shallow, mainly across western
Puerto Rico. Additionally, low-level winds are expected to
strengthen somewhat through the latter part of the short-term
period, maintaining breezy conditions, particularly along coastal
areas.

Late Friday night, moisture will increase rapidly as a weak tropical
wave approaches from the east. Precipitable water values are
forecast to increase to around 2.0-2.2 inches, accompanied by a
substantial increase in low- and mid-level relative humidity. This
could increase the frequency of shower activity across windward
coastal areas during Friday night period.

&&

.Long Term(Saturday through next Tuesday)...
Issued at 303 AM AST Wed Aug 26 2026

A brief, weak tropical wave will move quickly across the region
between late Friday night and Saturday morning, temporarily
increasing moisture and supporting passing showers and isolated
thunderstorms across Puerto Rico and the U.S. Virgin Islands. A
rapid drying trend is expected behind the wave, as a dominant
surface high settles over the central Atlantic and a mid-level
ridge builds across the region. Drier and more stable conditions
should become established by Sunday, with precipitable water
values falling below climatological normals to around 1.25 inches
through Monday morning.

Uncertainty increases during the second half of the forecast
period, as local conditions will depend on the track and future
intensity of tropical wave AL96, currently south-southwest of the
Cabo Verde Islands. Latest guidance still suggests the system will
pass northeast of the region between Monday afternoon and
Wednesday. Nevertheless, its evolution will continue to be
monitored for potential indirect impacts. Given the uncertainty,
residents and local interests should monitor subsequent forecasts
as AL96 moves across the Atlantic.

Meanwhile, seasonal to above-seasonal 925-mb temperatures will
persist throughout the period, resulting in elevated to possibly
significant heat risks each day.

&&

.AVIATION...
(18Z TAFS)
Issued at 226 PM AST Wed Aug 26 2026

Mainly VFR conds expected across all terminals. Saharan dust will
maintain HZ with VIS generally above 6SM. Increasing moisture
tonight will favor more frequent SHRA after 26/22Z, particularly
across windward PR/USVI terminals, but impacts should remain
minimal. SHRA/TSRA development is expected Thu aft, with VCTS at
TJPS/TJBQ after 27/17Z. E-ESE winds at 10-15 kt with sea breeze
variations, becoming lighter overnight.

&&

.MARINE...
Issued at 226 PM AST Wed Aug 26 2026

Surface high pressure across the central Atlantic will continue to
support a moderate east-to-east-northeasterly steering flow for the
rest of today, becoming more east-to-east-southeast tomorrow onward.
Saharan dust concentrations will gradually decrease late tonight
into Thursday, followed by shower and thunderstorm activity across
the local Atlantic waters and passages. A weak long-period
northeasterly swell remains on forecast to arrive and spread
across the regional waters by tomorrow, Thursday morning. Showers
and isolated thunderstorms associated with a tropical wave are
forecast to stay mainly over the local Caribbean waters and
passages by late Friday night into Saturday. Winds may briefly
become moderate to locally fresh as the tropical wave moves across
the area, with seas between 3 and 5 feet, occasionally 6 feet;
small craft must exercise caution.

&&

.BEACH FORECAST...
Issued at 226 PM AST Wed Aug 26 2026

The risk of rip currents is expected to increase tonight, becoming
moderate along northern and eastern-exposed beaches of Puerto Rico
and the U.S. Virgin Islands. Beachgoers must exercise caution, as
life-threatening rip currents are possible along the surf zone. A
weak long-period northeasterly swell remains on forecast to
arrive and spread across the regional waters by tomorrow,
Thursday, though the latest guidance shows a minimal increase in
seas, with breaking waves between 3 and 5 feet. Therefore, the
risk will remain moderate for the next few days. Aside from rip
currents, beachgoers must remain weather alert as showers and
isolated thunderstorms can be expected each afternoon across
western coastal areas of Puerto Rico. Isolated thunderstorms
could produce gusty winds and lightning, and beachgoers should
seek shelter whenever they hear thunder.


&&

.FIRE WEATHER...
Issued at 226 PM AST Wed Aug 26 2026

Fire weather conditions became more favorable for rapid fire spread
late this morning, prompting the issuance of a Fire Danger Statement
(RFD) through 5 PM AST for portions of Puerto Rico and the U.S.
Virgin Islands. Low relative humidity values, sustained easterly
winds between 10 and 15 mph with higher gusts, and dry fuels will
continue to support elevated fire weather conditions through this
afternoon. The greatest concern remains across southern and
southwestern Puerto Rico, where fuels remain exceptionally dry.
Increasing moisture later today and tonight should promote better
humidity recovery and gradually reduce the fire weather threat.

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...Extreme Heat Warning until 5 PM AST this afternoon for
     PRZ001>005-007-008-010-011.

     Heat Advisory until 5 PM AST this afternoon for PRZ012-013.

VI...Heat Advisory until 5 PM AST this afternoon for VIZ001-002.

AM...None.
&&

$$

SHORT TERM/AVIATION/FIRE WEATHER...CVB
LONG TERM....GRS
MARINE/BEACH FORECAST...MNG
KEY MESSAGES...MNG/JC

NWS SJU Office Area Forecast Discussion