National Weather Service Today's Weather Impact Levels

839
FXCA62 TJSJ 031700
AFDSJU

Area Forecast Discussion
National Weather Service San Juan PR
100 PM AST Sat Oct 3 2026

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

.KEY MESSAGES...
Issued at 100 PM AST Sat Oct 3 2026

- Showers and thunderstorms will continue to bring localized
  heavy rainfall, flooding, frequent lightning, and gusty winds
  over the next few days, especially during the afternoon. The
  potential for more widespread and heavier activity will increase
  Wednesday into Thursday as moisture associated with a tropical
  wave moves into the region.

- Heat concerns will increase Sunday into Monday and remain
  elevated through much of next week.

- Marine conditions will become more favorable for small craft
  Sunday onward. A moderate risk of rip currents will continue
  along many north- and east-facing beaches through Sunday,
  briefly decrease Monday, and return Tuesday.

- Across the U.S. Virgin Islands, heat will remain the main
  concern, while shower activity may increase Wednesday into
  Thursday as deeper tropical moisture reaches the region.

&&

.Short Term(This evening through Monday)...
Issued at 100 PM AST Sat Oct 3 2026

Showers and thunderstorms left over from the afternoon should
gradually diminish with the loss of daytime heating, with some
activity lingering across the interior and western Puerto Rico
before fading this evening. Later tonight, a more typical
overnight pattern should return, with passing showers favoring
eastern Puerto Rico and the U.S. Virgin Islands. Winds will
become light and variable in many areas overnight, with lows in
the upper 70s across coastal areas and near 80 degrees in some of
the more exposed locations. Temperatures across the higher
elevations and interior valleys should fall into the lower 60s.

Sunday and Monday will feature a fairly typical diurnal pattern.
Low-level winds will gradually become more east-southeasterly
while the mid- to upper-level trough remains displaced near
Hispaniola, leaving Puerto Rico along its eastern periphery with
only modest large-scale forcing. Model guidance shows seasonal to
slightly above-seasonal moisture through the period, but
relatively modest mid-level moisture and weakening lapse rates
should limit the potential for more widespread or organized
convection. Therefore, daytime heating, sea-breeze convergence,
terrain effects, and localized moisture will remain the primary
drivers for afternoon shower and thunderstorm development, mainly
along the Cordillera Central and toward western and northwestern
Puerto Rico. General winds will remain around 10 to 15 mph, with
locally gusty winds near thunderstorms.

Heat concerns will increase Sunday into Monday as low-level
temperatures continue to rise. The focus each day will then shift
from heat during the late morning and early afternoon to localized
heavy rainfall and flooding concerns where thunderstorms develop.
Although flooding is expected to remain localized, the risk will
be greater in areas that have received repeated rainfall in recent
days, where soils remain moist and opportunities for drying have
been limited.

&&

.Long Term(Tuesday through next Friday)...
Issued at 100 PM AST Sat Oct 3 2026

For the long-term period, more seasonal conditions are expected
initially, with a broad high-pressure system over the central
Atlantic remaining the main surface feature. On Tuesday, an east-
southeasterly low-level flow will favor a relatively fair morning
with limited shower activity, followed by afternoon convection
supported mainly by lingering low-level moisture, daytime heating,
and local effects. Activity should focus toward the interior and
northwestern portions of Puerto Rico, while streamers from the
U.S. Virgin Islands, Vieques, and Culebra remain possible.

On Wednesday, moisture associated with a tropical wave passing
south of the islands should begin filtering into the CWA within
the east-southeasterly flow, increasing the frequency and
intensity of showers and thunderstorms across the local waters and
over the interior and northwestern portions of Puerto Rico.
Moisture should deepen considerably Wednesday into Thursday, with
PWAT values potentially reaching around 2.1 to 2.4 inches and
increasing moisture through the lower and mid-levels. By Thursday,
nearby mid- to upper-level troughing, including an upper-level
low near Hispaniola, may provide additional support aloft. Despite
rather modest lapse rates and relatively warm mid-level
temperatures, the combination of deeper moisture, daytime heating,
and periods of enhanced upper-level support should favor the most
active portion of the period Wednesday into Thursday. Locally
heavy rainfall and repeated downpours could increase the potential
for urban and small-stream flooding, with localized flash
flooding possible where the heaviest activity persists.

By Friday, a transition toward a drier pattern is expected as
deeper moisture moves away and mid-level moisture decreases
sharply. Lingering low-level moisture, daytime heating, and local
effects should still support afternoon convection, while a more
easterly low-level flow favors activity across the interior and
western half of Puerto Rico. A drier air mass should spread across
the islands Saturday, further limiting deep convection. Heat will
remain another concern through much of the period, with the low-
level thermal profile remaining warm and potentially becoming
particularly unfavorable for heat impacts around Thursday across
coastal, urban, and lower-elevation areas.

&&

.AVIATION...
(18Z TAFS)
Issued at 100 PM AST Sat Oct 3 2026

Afternoon SHRA/TSRA will cont thru 03/21-23Z, with brief impacts
possible at TJBQ/TJPS. Trade-wind streamers may affect TJSJ/USVI
terminals thru 03/18-19Z. Brief MVFR/IFR CIG/VSBY, lightning, and
gusty/VRB winds are possible. E winds 10-15 kt will transition to
light/VRB btwn roughly 03/20-21Z and 04/03-04Z, depending on
terminal and local influences. Passing SHRA/VCSH will remain
possible overnight into the morning, with winds increasing again
aft 04/12-14Z from the ESE at 10-15 kt.

&&

.MARINE...
Issued at 100 PM AST Sat Oct 3 2026

Generally favorable marine conditions are expected across most of
the regional waters under a typical easterly trade wind pattern,
though locally choppy conditions will persist through tonight
across some of the more exposed waters and passages. Winds and
seas will gradually ease Sunday into early next week, resulting in
more favorable conditions for small craft. Afternoon thunderstorms
affecting the western and northern coastal waters may produce
locally hazardous marine conditions, including gusty winds, higher
seas, and frequent lightning.

&&

.BEACH FORECAST...
Issued at 100 PM AST Sat Oct 3 2026

A moderate risk of rip currents will continue through Sunday,
mainly along the north- and east-facing beaches of Puerto Rico,
Culebra, Vieques, and portions of the U.S. Virgin Islands. A brief
improvement is expected Monday, with a low risk across most
beaches, before moderate rip current conditions return Tuesday
along many north- and east-facing beaches.

Thunderstorms developing near the western and northern coastal
areas during the afternoon may also produce locally hazardous
beach conditions, including frequent lightning. Increasing heat
will be another concern Sunday into Monday, especially along
exposed coastal areas during the late morning and early afternoon.
Beachgoers should continue to check the latest forecast before
heading to the beach, as conditions may change from day to day.

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...None.
VI...None.
AM...None.
&&

$$

.EVE...CAM/LIS/RVM
.MID...CVB
.DAY...ICP/MRR

NWS SJU Office Area Forecast Discussion