796
FXCA62 TJSJ 071842
AFDSJU

Area Forecast Discussion
National Weather Service San Juan PR
242 PM AST Sun Dec 7 2025

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

.KEY MESSAGES...
Issued at 200 PM AST Sun Dec 7 2025

* Fair weather conditions are expected through the first part of
  the workweek. However, showers embedded in the trades will move
  during the nighttime over portions of the islands, and
  particularly from midweek onward.

* Winds will increase late in the week, leading to breezy to windy
  conditions across coastal and elevated areas by Thursday and
  Friday. Lightweight outdoor items may be blown around in exposed
  locations.

* For the U.S. Virgin Islands, quick passing showers are expected
  during the night and early morning hours. Sunny to partly cloudy
  during the day. Winds will become noticeably stronger late in
  the week.

* Marine and beach conditions will deteriorate during the second
  part of the workweek as increasing winds and an incoming long-
  period northerly swell raise seas and rip current risks.
  Hazardous surf and Small Craft Advisories are likely.

&&

.Short Term(This evening through Tuesday)...
Issued at 200 PM AST Sun Dec 7 2025

Sunny to partly cloudy skies prevailed across Puerto Rico and the
U.S. Virgin Islands through the day. Scattered showers were noted
early in the morning hours, mostly across the local waters and
over portions of southeastern PR. Maximum temperatures were from
the mid to upper 80s across the lower elevations of the islands,
and from the upper 70s to low 80s across the higher elevations of
Puerto Rico. The wind was from the east between 10 and 15 mph
with sea breeze variations and higher gusts at times.

For the rest of the short-term period, a strong mid-to upper-
level ridge building northeast of the local area will continue to
promote overall fair weather conditions. The precipitable water
content is forecast to drop well below normal levels, and range
between 1.00-1.35 inches. The best moisture content will remain
trapped below 850mb. Winds will shift from the east to southeast as
the surface high pressure over the central Atlantic shifts
further east over the Azores. This will bring patches of moisture
embedded in the trades at times, but particularly during the
nighttime. Therefore, passing showers with limited rainfall
accumulations are expected over the USVI and across the eastern
portions of PR during this period. Across western PR, locally
induced afternoon showers are expected each day, with minor
flooding concerns.

Also, sunny skies and southeasterly winds will promote normal to
warmer than normal daytime temperatures across the islands on
Monday and Tuesday.

&&

.Long Term(Wednesday through next Saturday)...
Issued at 449 AM AST Sun Dec 7 2025

A persistent and increasingly dominant mid-level ridge will govern
the period, maintaining well-below-normal mid-level moisture. Recent
model cycles show 700-500 mb relative humidity frequently dipping
below 20 percent and at times near 10 percent, supporting a strong
and persistent inversion based near 850 mb through most of the
forecast period. This pattern will continue to favor stable
conditions and suppress deep convection for the most part. However,
occasional shallow moisture surges embedded in the trade winds will
periodically lift the inversion height above the 700 mb layer,
allowing for an uptick in passing showers. These events will favor
the overnight and morning hours across windward coastal areas.
During the afternoons, isolated to scattered showers remain possible
across the interior and western Puerto Rico, but any thunderstorms
that develop will be short-lived and very isolated. No significant
flooding threat is expected.

Toward the latter part of the period, surface high pressure over the
central Atlantic is forecast to strengthen while a frontal boundary
approaches from the northwest. This will tighten the pressure
gradient across the northeastern Caribbean and result in breezy to
windy conditions, especially across coastal and elevated areas from
late week into the weekend. These winds may cause unsecured or
lightweight outdoor items to blow around and could produce localized
minor impacts in areas exposed to stronger gusts.

Overall, conditions will remain largely stable with shallow
convection, limited rainfall amounts, and a notable increase in
winds late in the workweek into the weekend.

&&

.AVIATION...
(18Z TAFS)
Issued at 200 PM AST Sun Dec 7 2025

Mainly VFR conditions are expected to prevail across all terminals
during the next 24 hours. Brief iso -SHRA could move overnight
across the USVI and eastern PR terminals. The 07/12z TJSJ sounding
indicated ESE winds up to 22 kt blo FL050.

&&

.MARINE...
Issued at 200 PM AST Sun Dec 7 2025

Light to moderate east to southeasterly trades are expected to
prevail through early in the workweek. By midweek, strengthening
high pressure north of the region will tighten the pressure
gradient and increase easterly winds, allowing seas to build
across the Atlantic waters and exposed passages. At the same time,
a long- period northerly swell arriving during the second part of
the week will further worsen conditions. Hazardous seas building
between 6 and 8 feet are expected Thursday into Friday, with Small
Craft Advisories likely. A gradual improvement remains possible
over the weekend as winds and swell ease.

&&

.BEACH FORECAST...
Issued at 200 PM AST Sun Dec 7 2025

A moderate risk of rip currents risk will persist through midweek
along the northern beaches of the islands. On Thursday, a long
period northerly swell will build seas up to 8 feet across the
Atlantic waters and portions of the local passages through early
in the weekend. This swell will cause large breaking waves along
the Atlantic coastline of the islands, promoting rough surf
conditions and life-threatening rip currents.

&&

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

$$

SHORT TERM...DSR
LONG TERM....CVB
AVIATION...DSR
BEACH/MARINE...DSR

NWS SJU Office Area Forecast Discussion