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820
FXCA62 TJSJ 191839
AFDSJU

Area Forecast Discussion
National Weather Service San Juan PR
239 PM AST Fri Dec 19 2025

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

.KEY MESSAGES...
Issued at 212 PM AST Fri Dec 19 2025

* Mostly fair weather will persist for the rest of the day and into
  the upcoming weekend, with passing showers and slightly warmer
  maximum temperatures.

* In the U.S. Virgin Islands, mostly stable weather is expected,
  with partly cloudy skies and minimal shower activity.

* A wet and unstable weather pattern is forecast for the upcoming
  workweek, with a high chance of widespread showers and isolated
  thunderstorms. Residents and visitors are urged to stay tuned for
  further updates.

* Hazardous marine and coastal conditions are forecast from Sunday
  onwards, as a northerly swell moves into the local waters.

&&

.Short Term(This evening through Sunday)...
Issued at 212 PM AST Fri Dec 19 2025

Mostly sunny skies prevailed across the islands today. Maximum
temperatures were from the mid to upper 80s across the lower
elevations. The wind was from the northeast between 10 and 20 mph
with higher gusts at times. Low-level clouds were developing over
the islands around noon, with little to no rainfall activity
detected over land areas as of 2 PM AST.

An upper-level ridge extending from the central Caribbean will
continue to provide stable condtions in general across the islands
for the rest of the short term period. However, patches of
moisture embedded in the moderate to fresh trade winds will bring
at times quick passing showers with mostly minor rainfall
accumulations across the windward areas of the islands during the
night and early morning hours. Across west/southwest PR, shallow
afternoon convection is possible each afternoon, however, rainfall
amounts are not expected to cause flood concerns. Regardless,
ponding of water in roads and other poor drainage areas is
possible.

Minimum temperatures will range from the low 60s across the higher
elevations of PR, to the upper 60s and low 70s across the lower
elevations of the islands. Daytime highs will continue from the
mid to upper 80s across the southern and western lower elevations
of PR.

&&

.Long Term(Monday through next Thursday)...
Issued at 500 AM AST Thu Dec 18 2025

Late in the weekend and into early next week, a weak mid- to
upper-level ridge will prevail across the region, supporting
generally stable atmospheric conditions. During this period,
precipitable water (PWAT) values are expected to remain below to
near seasonal climatological levels, ranging from 1.2 to 1.6
inches. At the surface, patches of low-level moisture will
continue to move through the area, producing brief passing showers
over windward sections of the islands. Rainfall accumulations
should remain limited, although isolated afternoon showers may
develop across western Puerto Rico. From midweek onward, the mid-
level ridge will gradually weaken as a polar trough departing the
eastern United States advances from the northwest. This pattern
change will increase atmospheric instability, with 500 mb
temperatures cooling to below-normal values between -7 and -10
degrees Celsius. A transition toward higher rain chances is
anticipated, with moderate probabilities (50 to 60%) for scattered
to numerous showers. At the surface, an associated frontal
boundary is forecast to approach the region around Wednesday into
Thursday (Christmas Eve and Christmas Day) and potentially move
across the area. As the front nears, moisture will increase, with
PWAT values rising to between 1.5 and 1.8 inches, within the
seasonal to above-normal range. The combination of cooler
temperatures aloft and increased moisture supports a more
unsettled pattern during the holiday period, including scattered
showers and isolated thunderstorms. Guidance, including the
Galvez-Davison Index, suggests the potential for shallow
convection with isolated thunderstorm development. Periods of
locally heavy rainfall may occur, which could elevate the risk of
localized flooding in flood-prone and poorly drained areas,
including ponding on roadways. At this time, the extended forecast
indicates a limited flood risk. Also, cooler temperatures are
expected in the wake of the possible frontal passage.

&&

.AVIATION...
(18Z TAFS)
Issued at 212 PM AST Fri Dec 19 2025

Mainly VFR conditions are expected to prevail across all terminals
during the next 24 hours. Brief passing -SHRA should cause mostly
VCSH across the USVI terminals and TJSJ. The wind will prevail
from the ENE btw 15-20 kt blo FL050.

&&

.MARINE...
Issued at 212 PM AST Fri Dec 19 2025

A weak surface low northeast of the region and a surface high
pressure building over the western Atlantic will promote moderate
to locally fresh (15-20 kt) east to northeast winds during the
next few days. These winds, combined with additional pulses of
northerly swells, will promote hazardous seas for small craft,
particularly across the Atlantic waters and local passages from
Saturday evening through Sunday. Small Craft Advisories conditions
are expected due to seas building up to 7 feet.

&&

.BEACH FORECAST...
Issued at 212 PM AST Fri Dec 19 2025

Fading northerly swell will continue to cause life-threatening rip
currents along the northern beaches of PR and Culebra through
this evening. Another long period northerly swell and increasing
wind-driven seas will cause rough surf conditions and life-
threatening rip currents once again from late Saturday through at
least Monday, across all east and north facing beaches of the
islands. Please follow the guidance of lifeguards, beach patrol
flags, and signs.

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...High Rip Current Risk until 6 PM AST this evening for PRZ001-002-
     005-008-012.

VI...None.
AM...Small Craft Advisory from noon Saturday to noon AST Sunday for
     AMZ711.

&&

$$

SHORT TERM...DSR
LONG TERM....YZR
AVIATION...DSR

NWS SJU Office Area Forecast Discussion