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157
FXCA62 TJSJ 050838
AFDSJU

Area Forecast Discussion
National Weather Service San Juan PR
438 AM AST Fri Dec 5 2025

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

.KEY MESSAGES...
Issued at 431 AM AST Fri Dec 5 2025

 * Limited shower activity is forecast for today, with mostly
   clear skies in the morning and afternoon.

 * Seasonal daytime temperatures will persist over the islands
   today into the weekend, with temperatures in the upper 80s
   along the coastal areas and even in the low 90s across southern
   coastal areas.

 * Stable weather conditions are forecast for the weekend into
   the upcoming workweek, with some passing showers but no flood
   threat across the islands.

 * There is a moderate risk of rip currents across all northern
   coastal areas, including St. Thomas and St. Croix.

&&

.Short Term(Today through Sunday)...
Issued at 431 AM AST Fri Dec 5 2025

Today through Sunday...

Conditions across Puerto Rico and the U.S. Virgin Islands remained
tranquil, characterized by mostly clear to partly cloudy skies.
Satellite and radar observations showed a few passing showers moving
over the local Atlantic and Caribbean waters; however, some of these
showers moved over the windward portions of the islands, resulting
in minimal accumulations. Overnight temperatures were observed in
the low to mid 60s along the higher elevations of Puerto Rico, while
they remained in the low to mid 70s along the lower elevations.

Today, a mid-to upper-level ridge extending from the west will
promote the intrusion of drier air and stable conditions aloft. This
ridge is projected to be the predominant synoptic feature for the
upcoming days, thus maintaining fair weather conditions across the
islands with very limited rainfall. Despite these conditions,
locally induced afternoon showers cannot be ruled out over central
and western Puerto Rico each day. By late Saturday into Sunday, a
surface high pressure system will begin to build north of the area,
supporting drier conditions into early next week. However, patches
of low-level moisture will move into the area on Sunday, promoting
the development of a few showers across the region. Seasonal
temperatures will prevail across the region during the weekend,
ranging from the mid to upper 80s along the lower elevations of the
islands and from the upper 70s to low 80s along the central mountain
range of Puerto Rico. Overnight lows are expected to settle between
the low to mid 60s in the higher elevations and the low to mid 70s
in the lower elevations, ideal conditions for holiday festivities
and the traditional "parrandas" this weekend.

&&

.Long Term(Monday through Friday)...
Issued at 431 AM AST Fri Dec 5 2025

The long-term forecast remains on track under a favorable stable
weather column across the islands. A strong and stalled mid to
upper-level ridge expanding in the central Atlantic will be the
main weather feature during the period.These features will hold a
stable weather pattern with warmer conditions aloft and a strong
trade wind cap inversion that limits vertical development across
the islands. Under this pattern, and as suggested by the 500 MB
temperatures in the -5 degrees, thunderstorm activity is not
anticipated. Although a lightning threat is not forecasted,
diurnal heating can still induce short-lived thunderstorms. Although
very stable conditions will prevail, a strong surface high
pressure over the Central Atlantic will drag patches of trapped
moisture at 850 MB. According to the global model guidance,
patches of trapped moisture with precipitable water values from
1.4 to 1.6 inches, close to the climatological normals, will move
in and out of the region embedded in the trade winds. Therefore,
in the afternoon, brief passing showers are possible due to
diurnal heating and local effects. Surface winds will remain
mostly from the east as the surface high pressure remains in the
Central Atlantic, and veering winds are forecast from Monday
onwards as the surface high pressure builds further into the
Central and Eastern Atlantic.

By midweek, as the surface high pressure establishes across the
central Atlantic, a tight in the pressure gradient will result in
breezy conditions. Additionally, since the surface winds will
remain east-southeasterly and plenty of sunshine will be present
due to the lack of instability, daytime temperatures will remain
just slightly above seasonal levels across the islands. According
to the global model guidance, 925 MB temperatures suggest warmer
conditions from Monday onwards, with Tuesday the warmest day of
the long term.

&&

.AVIATION...
(06Z TAFS)
Issued at 431 AM AST Fri Dec 5 2025

VFR conds expected across all terminals during the fcst period.
Mainly fair weather conds expected today; however, few passing
showers moving across portions of Puerto Rico and the USVI will
result in VCSH across all TAFs sites thru 05/14Z. Winds will remain
from the ENE at less than 10 kt thru 05/13-14Z, increasing between
12 to 16 kt thru 05/22-23Z, with higher gusts and sea breeze
variations.

&&

.MARINE...
Issued at 431 AM AST Fri Dec 5 2025

Today, an extending surface high pressure will dominate the
islands, producing moderate easterly winds and seas reaching up to
5 feet. A drier air mass is also moving across the region, which
will limit shower activity throughout the day. Global model
guidance indicates that energy from an incoming northerly swell
will reach the northern offshore Atlantic waters, likely leading
to higher seas and hazardous marine conditions. An increase in
surface winds will result in wind-driven seas, and energy from a
north-northwesterly swell will increase seas across the Atlantic
waters and the local passages.

&&

.BEACH FORECAST...
Issued at 431 AM AST Fri Dec 5 2025

There is a low to moderate risk of rip currents across the
northern and northeastern coastal areas of Puerto Rico, Culebra,
St. Thomas, and St. Croix. Global model guidance indicates that
energy from an incoming northerly swell will reach the northern
offshore Atlantic waters, likely leading to higher seas and
hazardous marine conditions. An increase in surface winds will
result in wind-driven seas, and energy from a north-northwesterly
swell will increase seas across the Atlantic waters, the local
passages, and the locally exposed beaches across the islands,
including the U.S. Virgin Islands.

&&

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

$$

SHORT TERM & AVIATION...GRS
LONG TERM, MARINE & BEACH FORECAST....LIS

NWS SJU Office Area Forecast Discussion