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738
FXCA62 TJSJ 141837
AFDSJU

Area Forecast Discussion
National Weather Service San Juan PR
237 PM AST Tue Jul 14 2026

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

.KEY MESSAGES...
Issued at 225 PM AST Tue Jul 14 2026

 * A Heat Advisory remains in effect through 5 PM AST this
   afternoon due to dangerous temperatures and heat indices across
   all coastal and urban areas of Puerto Rico and the U.S. Virgin
   Islands.

 * A drier airmass along with high concentrations of Saharan dust
   will continue to spread across the region, promoting hazy
   skies, reduced visibilities, poor air quality and limited
   shower activity.

 * A disturbance will reach the area by Thursday, increasing
   moisture and the potential for showers and thunderstorms.
   across the islands.

 * Breezy conditions will maintain choppy seas for mariners and a
   moderate risk of rip currents across most local beaches.

&&

.Short Term(This evening through Thursday)...
Issued at 225 PM AST Tue Jul 14 2026

Dry, hot conditions and hazy skies prevailed across the islands
today, driven by a drier airmass and high concentrations of Saharan
dust. High temperatures reached the upper 80s to low 90s,
particularly along the coastal and urban areas of Puerto Rico and
the U.S. Virgin Islands, where heat indices exceeded 105F.
Meanwhile, highs in the mountains ranged from the low to mid-80s,
with some valley areas in central Puerto Rico reaching the upper
80s. The Luis Munoz Marin International Airport in San Juan
reported a maximum temperature of 81F by early afternoon. A Heat
Advisory remains in effect until 5 PM AST across all urban and
coastal areas of Puerto Rico and the U.S. Virgin Islands.

For the rest of the afternoon, dry conditions and high
concentrations of Saharan dust will continue to dominate across the
islands. Despite the dry airmass, a brief shower cannot be ruled out
due to daytime heating and local effects, particularly over portions
of western Puerto Rico.

A strengthening high-pressure over the central Atlantic and a mid-
level ridge will continue to dominate over the next few days. This
setup will promote a drying trend that is expected to persist
through Wednesday, dropping precipitable water (PWAT) values below
the climatological normal to 1.20-1.25 inches. While Saharan dust
will gradually decrease on Wednesday, moderate to high
concentrations will still persist across the region tomorrow.
Sensitive groups, particularly those with respiratory illnesses or
allergies, are advised to limit prolonged outdoor exposure and
take necessary precautions due to reduced air quality.

By Thursday, an upper-level disturbance is expected to approach the
northeastern Caribbean, resulting in a slight increase in
instability and moisture. PWAT values will rise to seasonal levels
of around 1.75 inches. This moisture, combined with favorable upper-
level dynamics, daytime heating, and local effects, will trigger the
development of showers and isolated thunderstorms across central and
western Puerto Rico. During this period, Saharan dust concentrations
will significantly diminish to trace levels, leading to improved air
quality.

During the next few days, daytime highs are projected to increase
into the 90s across coastal and urban areas during the early
afternoon, while overnight temperatures will remain unseasonably
warm as the Saharan dust layer traps heat and limits radiational
cooling. Therefore, heat indices are highly likely to reach
hazardous levels again on Wednesday. Residents and visitors are
strongly encouraged to practice heat safety measures to mitigate the
risk of heat-related illnesses.

&&

.Long Term(Friday through next Monday)...
Issued at 225 PM AST Tue Jul 14 2026

During the long-term period, Friday will have the highest
potential for rainfall as a weak upper-level low system interacts
with a low-level perturbation moving across the local area.
Moisture values are forecast to remain near seasonal normals, with
sufficient mid-level moisture to support scattered showers,
especially during the afternoon across the western sections of
Puerto Rico and overnight into the morning hours over the U.S.
Virgin Islands and eastern PR. While widespread flooding is not
expected, locally heavy downpours could lead to ponding of water
in low-lying and poor drainage areas. From Friday into the
upcoming workweek, low concentrations of Saharan dust are expected
to linger across the region. Although occasional hazy skies are
likely, dust concentrations should remain low enough to have only
minor impacts on visibility and rainfall coverage. Individuals
with respiratory conditions may still experience some discomfort
and should consider limiting prolonged outdoor exposure.

Saturday through Monday, a typical summertime pattern is expected.
A slightly drier air mass arriving on Saturday may limit shower
coverage, but daytime heating and local effects will continue to
support isolated to scattered afternoon showers over the interior
and western municipalities. By Sunday and Monday, cooler
temperatures aloft associated with a weak upper-level trough will
promote a modest increase in atmospheric instability, allowing
afternoon convection to become somewhat more active. Even so,
rainfall is expected to remain localized, with the primary hazards
being brief periods of heavy rain, gusty winds near stronger
thunderstorms, and isolated lightning strikes.

Warm to hot conditions will persist through the period as low-
level temperatures remain above averages. Heat indices will likely
exceed seasonal normals across urban and coastal areas. Residents
and visitors are encouraged to stay hydrated, take frequent breaks
in the shade or air conditioning, and avoid strenuous outdoor
activities during the hottest part of the day.

&&

.AVIATION...
(18Z TAFS)
Issued at 225 PM AST Tue Jul 14 2026

VFR conds will prevail across all terminals through the fcst
period. Limited VCSH/SHRA are more possible at TJBQ thru 14/23Z.
High concentrations of Saharan dust will result in HZ over the
islands, causing VIS reductions at all PR & USVI terminals. Gusty
conds will prevail, with E- ESE winds at around 15-19 kt with
gusts up to 30 kt 14/23Z, becoming light overnight at 5-10 kt
through 15/13Z.

&&

.MARINE...
Issued at 225 PM AST Tue Jul 14 2026

A surface high over the central Atlantic interacting with the
PanamaColombia low will maintain a tight pressure gradient across
the region, supporting moderate to locally fresh east-southeast
winds and moderate to choppy seas for the next few days. A drier air
mass, accompanied by moderate to high concentrations of Saharan
dust, will continue to spread across the region through early
Thursday, resulting in hazy skies and reduced visibility. A trade
wind perturbation is expected to move through the area around
Thursday, increasing the potential for passing showers and isolated
afternoon thunderstorms.


&&

.BEACH FORECAST...
Issued at 225 PM AST Tue Jul 14 2026

No changes were introduced to the beach forecast. The moderate risk
of rip currents continues across northern and eastern-exposed
beaches of Puerto Rico, including Culebra, and the U.S. Virgin
Islands; low elsewhere. Although the risk remains moderate,
beachgoers must exercise caution as life-threatening rip currents
are possible along the surf zone. The moderate risk should continue
for the next several days, though it may spread across most beaches
of the islands by the weekend. In addition to rip currents,
beachgoers must continue to stay updated on the weather conditions,
as moderate to high concentrations of Saharan Dust will spread
across the region, bringing hazy skies and deteriorating air
quality; sensitive groups must follow medical recommendations.
Shower and thunderstorm activity may increase on Thursday, bringing
gusty winds and isolated lightning near coastal areas of the western
side of Puerto Rico.

&&

.FIRE WEATHER...
Issued at 225 PM AST Tue Jul 14 2026

A dry air mass and Saharan dust will continue to dominate the
region today, keeping the fire danger risk elevated. This dry
weather pattern will cause relative humidity (RH) levels to drop
to critical threshold values between 40% and the low 50s during
the early afternoon hours. In addition to the low humidity, winds
will be favorable for rapid fire spread, blowing from the east-
southeast at 10 to 15 mph with higher gusts.

Because of these critical conditions, a Fire Danger statement has
been issued for most sections of the southern plains and across
the northern coastal sectors of the island. Any fires that ignite
in these areas could spread quickly and become difficult to
control. Additional Red Flag Warning conditions are briefly
possible; however, the limiting factor will be the south wind
component that can trigger changes in the RH values.

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...Heat Advisory until 5 PM AST this afternoon for PRZ001>005-007-
     008-010>013.

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

AM...None.
&&

$$

SHORT TERM...GRS
LONG TERM....MMC
MARINE/BEACH FORECAST...MNG

NWS SJU Office Area Forecast Discussion