980
FXCA62 TJSJ 131854
AFDSJU

Area Forecast Discussion
National Weather Service San Juan PR
254 PM AST Tue Jan 13 2026

...New SHORT TERM, LONG TERM, AVIATION...

.KEY MESSAGES...
Issued at 253 PM AST Tue Jan 13 2026

* Seasonal conditions will prevail across the region with passing
  trade-wind showers affecting the windward and coastal areas of
  Puerto Rico and the U.S. Virgin Islands during the morning and
  evening hours.

* Localized afternoon showers will lead to a limited flooding risk
  across portions of central and western Puerto Rico each day.

* A moderate risk of life-threatening rip currents will continue
  along the north and east-facing beaches of Puerto Rico, Culebra
  & St. Croix through the end of the workweek.

* Marine and coastal conditions will deteriorate this weekend with
  the arrival of a northwesterly swell and stronger winds. Residents
  and visitors are urged to follow the conditions closely as the
  week progresses.


&&

.Short Term(This evening through Thursday)...
Issued at 253 PM AST Tue Jan 13 2026

High-level cloudiness prevailed throughout most of the morning
across all the islands, accompanied by light to moderate showers
affecting the exposed waters and briefly streaking over the
eastern sides of the islands. As of 12 PM, satellite imagery
showed the cloudiness development, mostly across the interior into
the western interior. Therefore, shower activity developed across
those areas with light to moderate shower activity. Rainfall
accumulations from the Doppler Radar were minimal, with the
highest value in Trujillo Alto at almost half an inch. Daytime
temperatures were near seasonal values. According to unofficial
stations, temperatures were in the mid- to upper 80s across
coastal areas and near the upper 70s and lower 80s in the
interior.

For the rest of the period, the weather will remain mostly stable
as the mid- to upper-level ridge continues to dominate the
atmospheric pattern. Meanwhile, at the surface, a strong and broad
surface high pressure will continue to result in an easterly wind
flow. Under this surface pattern, a patch of shallow moisture will
filter in, with Precipitable Water Values of 1.2 inches, as shown
by GOES-derived satellite imagery, exceeding climatological
normal. These surface conditions will be enough to trigger a
variable weather pattern tonight, with occasional showers across
eastern sections of Puerto Rico and the U.S. Virgin Islands.
Weather conditions will slightly change as the broad surface high
pressure extends farther into the western Atlantic and as some
influence from the frontal boundary located north of the region.
As a result, veering winds will be present, and a southeasterly
flow will be predominant on Wednesday into Thursday. Under this
wind flow, moisture from the Caribbean will move into the islands,
peaking the 850-500 MB Relative humidity at the 75th percentile on
Wednesday. Therefore, the forecast calls for a more showery
pattern, with frequent showers across eastern sections and
afternoon convection across the interior and northwestern parts of
Puerto Rico. On Thursday, similar weather conditions will persist,
with precipitable water values similar to those moving into the
region, but with some instability as a deep-layer trough stalls
over the western Atlantic, weakening the ridge over the area. As a
result, colder temperatures are expected at 500 MB, with potential
for one or two thunderstorms, with the afternoon showers across
the interior and northwestern PR.

&&

.Long Term(Friday through next Monday)...
Issued at 502 AM AST Tue Jan 13 2026

On Friday, model guidance indicates that a frontal boundary will
remain north of the region, while a pre-frontal trough may enhance
low-level moisture convergence and atmospheric instability,
supporting a wetter pattern. Friday currently appears to have the
greatest rainfall potential, with a limited flood risk mainly
across western Puerto Rico during the afternoon hours. Isolated
thunderstorms cannot be ruled out. Precipitable water values are
forecast to range between 1.4 and 1.9 inches from Friday through
Saturday, near to above climatological normals for this time of
year.

Low-level winds will generally remain from the east to southeast
at 10 to 15 mph on Friday, then shift to the east to northeast by
Friday night into Saturday while increasing to 15 to 20 mph with
gusts up to 25 to 30 mph. Breezy to locally windy conditions are
expected Saturday and early Sunday, which may lead to loose outdoor
items being blown around, especially across exposed and coastal
areas.

From Sunday through Tuesday, precipitable water values are
expected to decrease to between 1.2 and 1.5 inches, with patches
of near-average moisture moving across the region. This will
support more variable but seasonable conditions, with passing
trade wind showers and limited convective development each
afternoon. No flooding concerns at this time.

A subtropical jet streak near 250 mb will establish a favorable
dynamic pattern from Tuesday night into Wednesday, supporting
upper-level divergence and an induced surface trough. As a result,
an increase in the frequency of showers is expected across the
forecast area under a northeasterly low-level wind flow. Continue
to monitor the forecast updates.

Temperature-wise, ensemble guidance continues to indicate near
seasonal to above-normal temperatures across Puerto Rico and the
U.S. Virgin Islands throughout the long-term period.

&&

.AVIATION...
(18Z TAFS)
Issued at 253 PM AST Tue Jan 13 2026

VFR conditions will persist across all TAF sites during the
period. VCSH to SHRA will continue near TJSJ, TJBQ & TJPS from now
through 13/22Z. Winds will persist from the E-NE up to 11 knots
with sea breeze variation, diminishing at 14/03Z./ Hi-Resolution
models show an increase in shower activity across the eastern TAF
sites from 13/23Z to 14/12Z. No significant operations are
forecast.

&&

.MARINE...
Issued at 253 PM AST Tue Jan 13 2026

A surface high pressure across the central Atlantic and a surface
trough to the north of the region will maintain gentle to moderate
east to northeast winds through Wednesday, then shifting from the
east to southeast by Thursday. This pattern will support passing
trade- wind showers, mainly across the Atlantic waters, with
occasional showers also moving through the Caribbean passages. By
Saturday, strengthening east to northeast winds and the arrival of
a long- period northerly swell will likely result in choppy to
rough seas, leading to hazardous marine conditions during the
weekend. Mariners are advised to continue monitoring the forecast.

&&

.BEACH FORECAST...
Issued at 253 PM AST Tue Jan 13 2026

A moderate risk of rip currents will continue for the next several
days along the northern and eastern beaches of Puerto Rico, as
well as Culebra and St. Croix, with breaking waves around 4 feet.
A moderate risk means that life-threatening rip currents are
possible within the surf zone, and beachgoers should exercise
caution at all times.

Conditions are likely to deteriorate over the weekend as winds
increase and the arrival of a long-period northerly swell. This
will lead to a high rip current risk across Atlantic exposed
beaches of Puerto Rico and the U.S. Virgin Islands. For more
location specific information, continue to monitor
weather.gov/beach/sju.

&&

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

$$

SHORT TERM/AVIATION...LIS
LONG TERM....YZR
PUBLIC, KEY MESSAGES, MARINE & BEACH FORECAST...GRS

NWS SJU Office Area Forecast Discussion