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247
FXCA62 TJSJ 040615
AFDSJU

Area Forecast Discussion
National Weather Service San Juan PR
215 AM AST Wed Nov 4 2026

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

.KEY MESSAGES...
Issued at 200 AM AST Wed Nov 4 2026

- Another day with warm and humid conditions, particularly across
  urban and low-lying areas of the islands. Therefore, the Heat
  Advisory remains in effect from 10 AM through 4 PM AST.

- Showers and thunderstorms are expected across the interior
  extending to northwards Puerto Rico, leading to ponding of
  water over roadways and minor flooding.

- A wetter pattern is expected from Thursday through Saturday.
  Increasing moisture and slow-moving showers and thunderstorms
  could raise the flooding threat, including urban and small-
  stream flooding, with isolated flash flooding possible, as well
  as landslides.

- Another swell is forecast to arrive this Friday into the
  weekend, bringing hazardous seas and life-threatening rip
  currents. Refer to the Beach Forecast section for additional
  details.

&&

.Short Term(Today through Friday)...
Issued at 200 AM AST Wed Nov 4 2026

Partly cloudy skies prevailed across Puerto Rico and the US Virgin
Islands overnight, with a few showers reaching the eastern
municipalities of Puerto Rico. Winds remained light and variable,
while temperatures generally ranged from the upper 70s to lower
80s across urban and coastal areas, and from the upper 60s to 70s
across the higher terrain.

Another hot day is expected across Puerto Rico and the US Virgin
Islands today, with a Heat Advisory in effect from 10 AM through
4 PM AST. Abundant surface moisture and increasingly southerly
winds will contribute to heat indices ranging from 100 to 108
degrees Fahrenheit, particularly across urban and coastal areas,
while minor concentrations of Saharan dust may result in hazy
skies. Residents and visitors are urged to stay hydrated, limit
prolonged sun exposure, and follow health officials
recommendations to reduce the risk of heat exhaustion and heat
stroke. Meanwhile, as a surface low continues to develop along a
frontal boundary north of the region, additional tropical moisture
will spread across the islands, with precipitable water values
increasing to around 2.02.2 inches today. By the afternoon,
increasing moisture, daytime heating, and local effects will
support scattered to numerous showers and thunderstorms. Given the
light winds, showers and thunderstorms are expected to develop
initially along the Cordillera Central before spreading into other
portions of Puerto Rico. Some thunderstorms could produce heavy
rainfall, frequent lightning, and gusty winds, with slow movement
increasing the potential for urban and small-stream flooding.

Conditions will become increasingly favorable for widespread and
locally deep convection Thursday as deeper tropical moisture spreads
across the region. Both the GFS and ECMWF indicate increasing mid
level relative humidity and precipitable water values to around
2.3 inches. As surface winds become more southerly to
southwesterly, enhanced moisture transport and convergence will
favor showers and isolated thunderstorms over the surrounding
waters and coastal areas during the morning, followed by numerous
to widespread afternoon showers and thunderstorms, particularly
across the interior, northern and eastern sections of Puerto Rico.
This unsettled pattern is expected to continue into Friday, with
additional rainfall potentially exacerbating conditions in areas
affected previous days. Thursday remains the favored day for the
most widespread and heaviest rainfall, although the exact
distribution and magnitude will depend on the evolution.
Therefore, the risk of urban and small-stream flooding, localized
flash flooding, and landslides in steep terrain will increase,
potentially resulting in flooded roadways and rapid rises along
streams and rivers. Residents and visitors, particularly those in
flood-prone and landslide-prone areas, should monitor forecast
updates and heed any flood advisories or warnings.

Overall, forecast confidence remains moderate to high in the
transition toward a wetter and more convectively active weather
pattern through Friday. However, confidence is lower regarding the
precise location and timing of the heaviest rainfall.
Nevertheless, Thursday and Friday remain the primary periods of
concern for excessive rainfall and associated flooding impacts.

&&

.Long Term(Saturday through Wednesday)...
Issued at 200 AM AST Wed Nov 4 2026

Following the trend of the short term period, by Saturday,
atmospheric instability and available moisture will remain elevated.
Precipitable water (PWAT) will continue generally above normal (2
inches) as a southwesterly steering flow continues to bring tropical
moisture towards the islands. This tropical moisture will continue
to move northwards and upper-level trough and its corresponding
frontal low. Although the core of maximum instability is still
forecast to pass north of the area, this pattern will continue to
result in a generally WSW to W surface flow to start the period. 925
mb winds will increase to more seasonal levels on Saturday before
decreasing to more light and variable Sunday through at least early
Wednesday. Relative humidity from 850 to 700 mb and from 700 to 500
mb should remain at high end normal to above normal values for the
month on Saturday. Showers and t-storms are likely to develop to
start the period, generating elevated rainfall totals, primarily
across the southern, interior, northern and northeastern sectors of
Puerto Rico, as well as the U.S. Virgin Islands. This will result in
flooding (Risk level 2 of 4) especially across interior, northern
and northeastern Puerto Rico during the afternoon hours with these
showers and t-storms possibly moving east towards Vieques, Culebra
and the northern USVI.

With the upper trough and frontal low moving away from the area, a
transition to a more stable pattern with mid-to-upper level riding
is forecast Sunday through Wednesday. Models are in more agreement
in terms of moisture availability than in the past few days. PWAT
and RH values are forecast to fluctuate between normal to above
normal values during that period, with a sharper decrease towards
more normal values Tuesday into Wednesday. As mentioned above, 925
mb wind speeds will be on a decreasing trend Sunday onwards before
gradually increasing once again towards Wednesday. These lighter and
variable surface winds will gradually pick up from the ESE and then
E to end the period, albeit under a more southerly steering flow.
Although daytime heating and localized effects may still generate
scattered afternoon convection across the islands, a general
decrease in shower activity and intensity is expected when compared
to the short term period and Saturday, reducing the flood threat.
925 mb wind speeds are still forecast at above normal values for
most of the period. Please stay tuned for subsequent updates as the
forecast evolves.

&&

.AVIATION...
(06Z TAFS)
Issued at 200 AM AST Wed Nov 4 2026

VFR conditions across all TAF sites. However, SHRA/TSRA over the
interior and northern PR may cause tempo MVFR conds at TJPS, TJBQ,
and TJSJ through 04/22Z. Mostly VCSH expected across the rest of
the PR and USVI terminals. HZ due to suspended Saharan dust is
expected through late today, but VSBY should remain P6SM. Winds
will remain light from SE, with higher gust near the heaviest
afternoon shower activity.

&&

.MARINE...
Issued at 200 AM AST Wed Nov 4 2026

A developing low-pressure system north of Puerto Rico will weaken
the local pressure gradient Wednesday through Friday, resulting in
generally light winds shifting from southeast to south and
southwest, with periods of variable winds. Showers and thunderstorms
will increase across the regional waters, particularly Thursday and
Friday, producing locally gusty winds, reduced visibility, and
lightning. Seas will initially subside before a north-northwesterly
swell arrives Friday and builds through the weekend, creating
increasingly hazardous conditions for small craft across the
Atlantic waters and exposed passages. Swell effects could persist
into Monday, with another pulse of northeasterly swells arriving.

&&

.BEACH FORECAST...
Issued at 200 AM AST Wed Nov 4 2026

A moderate risk of rip currents will persist along north- and east-
facing beaches of Puerto Rico and portions of Culebra and the
northern U.S. Virgin Islands Wednesday through at least Friday. A
north-northwesterly swell arriving Friday will build through the
weekend, increasing surf and bringing a high risk of life-
threatening rip currents to exposed northern beaches Saturday and
Sunday and possibly early next week. A moderate risk will extend to
additional beaches, including portions of Vieques and St. Croix.

Thunderstorms will pose an additional hazard to beachgoers, with
isolated to scattered thunderstorms possible Wednesday and isolated
thunderstorms Thursday through Sunday. Beachgoers should leave the
water and seek shelter in a substantial building when they hear
thunder. Avoid swimming at beaches under a high rip current risk.

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...Heat Advisory from 10 AM this morning to 5 PM AST this afternoon
     for PRZ001>013.

VI...Heat Advisory from 10 AM this morning to 5 PM AST this afternoon
     for VIZ001-002.

AM...None.
&&

$$

SHORT TERM/AVIATION...MMC
LONG TERM...MRR
MARINE/BEACH FORECAST...CAM

NWS SJU Office Area Forecast Discussion