National Weather Service Today's Weather Impact Levels

290
FXCA62 TJSJ 020914
AFDSJU

Area Forecast Discussion
National Weather Service San Juan PR
514 AM AST Tue Dec 2 2025

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

.KEY MESSAGES...
Issued at 438 AM AST Tue Dec 2 2025

* There is a moderate risk of life-threatening rip currents along
  the north and east-facing beaches in PR and the US Virgin
  Islands today and through much of the forecast period.

* We have a slight risk of thunderstorms, especially in the
  interior and mountain areas of PR, St. Thomas, and St. John this
  afternoon.

* St Thomas, St John, and the mountain areas in PR have a slight
  risk of flooding rains this afternoon into the evening.

* Residents and visitors in the US Virgin Islands and the windward
  portions of Puerto Rico can expect occasional passing showers
  each day.

&&

.Short Term(Today through Thursday)...
Issued at 438 AM AST Tue Dec 2 2025

Overnight hours remained relatively tranquil, with most showers
staying over the surrounding waters. Temperatures stayed in the 70s
along coastal areas and in the 60s across the higher terrains. Winds
were light and variable across Puerto Rico and the U.S. Virgin
Islands.

The latest precipitable water models continue to show near-seasonal
moisture values over the local area, with slightly higher PWATs to
the northeast in association with an induced surface trough. Model
guidance favors this trough gradually drifting across the islands
over the next couple of days, weakening the prevailing NEE flow and
allowing deeper moisture to pool across the region. At the same
time, 500 mb temperatures are forecast to drop to around 9 degrees
Celsius, falling below the 25th percentile for this time of year.
Cooler mid-levels, combined with higher moisture and favorable upper-
level ventilation, will support a more unstable environment. As a
result, deeper cloud development and a vertical development in
showers and isolated thunderstorms are expected, particularly during
the afternoon when daytime heating maximizes convective growth.
Current guidance highlights today as the most active day in the
short-term period. Nevertheless the wet pattern should prevail
through Thursday. Weakening winds will also increase the likelihood
that any showers or thunderstorms that form move slowly or remain
nearly stationary. If that occurs, localized flooding could develop,
especially across the eastern half and interior sections of Puerto
Rico. Although model guidance support rainfall amounts capable of
producing minor flooding impacts, confidence remains limited due to
uncertainty in cloud cover. If widespread clouds develop early,
daytime heating and resulting convection may be weaker than the
rainfall signals suggest. For this reason, flooding potential is
present but remains under the limited threshold.

A similar pattern is anticipated on Wednesday, with afternoon
convection possible, though current model trends point to somewhat
lower coverage and intensity than what is expected today and
Thursday. Also models indicates a slight increase in 925 mb
temperatures through mid-week, with Wednesday likely being the
warmest day. While localized heat indices may briefly approach 100
F, probabilities keep values below Heat Advisory criteria. As a
result, no significant heat-related impacts are anticipated during
the forecast period.

&&

.Long Term(Friday through Tuesday)...
Issued at 438 AM AST Tue Dec 2 2025

A mid- to upper-level ridge building from the west over the
northeast Caribbean will likely displace a trough aloft eastward
and away from the region by Friday, promoting a more stable
atmosphere. This ridge aloft is expected to build and persist
throughout the forecast period, supporting subsidence and dry air
aloft, and reinforcing the trade-wind inversion.

With this pattern in place, an advective trade-wind regime will
prevail. As a result, there is a low (10-20%) to moderate (30-50%)
chance of occasional passing showers across the windward areas of
Puerto Rico and the US Virgin Islands each day. Afternoon
convection across the interior and western Puerto Rico also
carries a low to moderate chance of developing daily, but current
guidance does not indicate a flooding threat at this time.

Overall, expect a mix of sunshine and clear skies with periods of
passing clouds. Windward locations can anticipate occasional brief
showers carried by the prevailing trades.

&&

.AVIATION...
(06Z TAFS)
Issued at 438 AM AST Tue Dec 2 2025

VFR conditions are expected to prevail across all TAF sites. Brief
periods of MVFR are possible after 17Z at TJSJ, TIST, and TJPS due
to increasing afternoon shower and thunderstorm activity. Winds will
remain light from the NE, with occasional higher gusts near any
stronger shower activity. After 02/17Z, VCTS, VCSH and -RA will be
possible at TJSJ, TIST, and TJPS mainly associated with slow-moving
convection.

&&

.MARINE...
Issued at 438 AM AST Tue Dec 2 2025

A surface trough northeast of the islands will promote moderate
northeasterly winds today, then winds will shift more from the
southeast to south tonight into Wednesday, as the trough moves
westward near the region. Afternoon thunderstorms will form the next
few days due to the proximity of the surface trough. A small easterly
swell will spread across the local waters through Thursday.
Additionally, a surface high pressure across the Central Atlantic
will promote the return of the moderate to locally fresh east to
northeast winds the second part of the week.

&&

.BEACH FORECAST...
Issued at 438 AM AST Tue Dec 2 2025

A small easterly swell will promote a moderate risk of rip
currents along the north and east facing beaches of Puerto Rico,
including Vieques and Culebra, and across the U.S. Virgin Islands.
These conditions will persist most of the week due to the small
easterly to northeasterly swell and increasing winds from Thursday
onward. A moderate risk means that life-threatening rip currents
are possible and can quickly pull swimmers away from shore.

Even where the risk is lower, rip currents can still form near
groins, jetties, reefs, and piers. Visitors and residents are
strongly encouraged to swim near a lifeguard and remain aware of
changing conditions.

There is a slight risk of thunderstorms, especially during the
afternoon hours, across western Puerto Rico. This activity could
move across coastal areas at times, increasing the risk of
lightning strikes.

&&

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

$$

SHORT TERM/AVIATION...MMC
KEY MESSAGES/LONG TERM/MARINE/BEACH FORECAST....CAM

NWS SJU Office Area Forecast Discussion