National Weather Service Today's Weather Impact Levels

267
FXCA62 TJSJ 101844
AFDSJU

Area Forecast Discussion
National Weather Service San Juan PR
244 PM AST Tue Mar 10 2026

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

.KEY MESSAGES...
Issued at 244 PM AST Tue Mar 10 2026

* Fresh to locally strong winds will continue to result in choppy
  to rough seas across the offshore Atlantic waters. A Small Craft
  Advisory remains in effect through at least noon Wednesday.
  Slight improvement in marine conditions is expected thereafter,
  at least through Saturday.

* Breezy to locally windy conditions will continue across Puerto
  Rico and the U.S. Virgin Islands through Wednesday, becoming
  lighter on Thursday and Friday.

* Frequent passing trade wind showers are expected to move across
  the region for the rest of the afternoon, and a limited flood
  threat persists across western Puerto Rico.

* Across the U.S. Virgin Islands, quick passing trade wind showers
  will occur at times, with a drying trend expected by the end of
  the week.

&&

.Short Term(This evening through Thursday)...
Issued at 244 PM AST Tue Mar 10 2026

A broad surface high pressure over the central Atlantic will
slowly shift eastwards by the end of the workweek. In response,
breezy conditions will continue through at least tomorrow, with
trade winds turning more east-northeast. Wind speeds are expected
to peak today around 22 knots, then gradually decrease to 12 knots
by late Thursday as an induced low-level trough moves from the
north/northeast. For the rest of this afternoon, today`s morning
sounding indicated a very stable atmosphere, with a pronounced
trade wind inversion near the 850 mb level, capping the atmosphere
with dry air directly above it. The precipitable water (PWAT)
content is currently on the lower end of seasonal values at 1.42
inches. Also, the sounding indicated a low surface CAPE of 64
J/kg, meaning deep convective thunderstorms are highly unlikely
today; therefore, minor adjustments were made to the weather
grids.

In terms of moisture content and shower potential, model guidance
has been persistent, suggesting fluctuations in PWAT content from
wet/dry to dry/wet periods as trade winds continue to carry patches
of moisture from the Tropical Atlantic, and due to the approaching
upper-level trough and associated lower-level trough late in the
short-term period. Having said that, isolated thunderstorms were
left for Wed-Thu over western PR, as the proximity of the trough
could enhance the expected diurnally induced convection.

The overall weather pattern supports passing trade wind showers
across the USVI and east/northeast sections of PR during the
overnight/morning hours, followed by afternoon showers developing
over the west and southwest quadrant of PR each day.

&&

.LONG TERM(Friday through Tuesday)...
Issued at 331 AM AST Tue Mar 10 2026

Unstable weather conditions will persist across the local islands
for the first part of the long-term forecast. At the upper levels, a
strong jet stream exceeding 100 mph will continue to generate
divergence aloft, resulting in favorable conditions for vertical
development of showers and thunderstorms. Combined with this upper-
level feature, recent model guidance suggests decent amounts of
moisture in the lower levels, with precipitable water values
slightly reaching climatological normals of 1.20 to 1.50 inches.
This pattern will drive the appropriate conditions for afternoon
convection, especially across the interior and northeastern
sections, as well as the southwest quadrant due to a wind shift more
toward the east-northeast. From Saturday onward, a broad surface
high pressure will shift further east into the western Atlantic,
reducing the pressure gradient and allowing the islands to
experience moderate easterly winds of 10 to 15 mph, with gusty
conditions near the coastal areas and in the vicinity of showers.
For much of Saturday, slightly drier air will dominate, limiting
shower chances across the region. However, on Sunday, increased
moisture from the east will filter into the region, enhancing
convective chances once again. As a result, Saturday looks to be the
day with the least rainfall potential, while Sunday shapes up as the
wettest day of the weekend. Upper-level instability will persist
through Saturday into Sunday, continuing to support shower and
thunderstorm development during the afternoon hours.

For Monday into Tuesday, stable conditions will dominate at the
upper levels, characterized by a mostly zonal flow and warmer
temperatures at 500 mb, effectively suppressing deep convective
development across the region. The lack of upper-level support,
combined with a more stable atmospheric profile, will limit the
vertical development of showers throughout the day. As a result,
mostly sunny skies are expected across coastal and nearshore areas,
with good periods of sunshine throughout the day. Although the
overall pattern will remain stable, the afternoon diurnal heating
peak will still be sufficient to trigger isolated convective showers
across the interior sections. Rainfall amounts associated with these
afternoon showers are expected to remain light to moderate, with no
significant flooding concerns anticipated at this time. Temperatures
will trend warmer under the influence of a stable, mostly sunny
pattern, with coastal highs expected to reach the upper 80s to near
90 degrees.

&&

.AVIATION...
(18Z TAFS)
Issued at 244 PM AST Tue Mar 10 2026

Mainly VFR conditions are expected to prevail across all terminals
through the forecast period. However, quick trade wind SHRA will
move at times across the area terminals, causing brief MVFR cigs.
Surface winds will continue at 15-20 kt from the E-ENE with sea
breeze variations and higher gusts thru late this afternoon.

&&

.MARINE...
Issued at 244 PM AST Tue Mar 10 2026

A broad surface high pressure system across the Atlantic will
promote moderate to fresh easterly winds, keeping seas 6 to 7
feet across the offshore Atlantic waters. Therefore, a Small Craft
Advisory will remain in effect for that zone at least through
Wednesday morning. Across the nearshore and coastal waters, seas
will remain between 5 and 6 feet, resulting in choppy marine
conditions. Small craft operators are urged to exercise caution.
Improving marine conditions are forecast for Thursday and Friday,
as winds are expected to subside to gentle to moderate and seas
decrease to between 3 and 5 feet. However, winds are forecast to
increase again around Saturday night into Sunday, leading to a
deterioration in marine conditions once again.

&&

.BEACH FORECAST...
Issued at 244 PM AST Tue Mar 10 2026

For the rest of this afternoon and tonight, there is a moderate
risk of rip currents across most beaches of Puerto Rico and the
U.S. Virgin Islands. Easterly winds will remain breezy to windy
due to a broad surface high pressure in the Atlantic, resulting in
choppy seas and increasing the potential for life-threatening rip
currents in the surf zones. Beachgoers should continue to
exercise caution. Similar conditions are anticipated tomorrow,
Wednesday.

By Thursday and Friday, winds are expected to subside. Although
the rip current risk will remain moderate along north and east-
facing beaches of Puerto Rico, Vieques, Culebra, and St. Croix,
the risk will be low along the western and southern exposed
beaches of the islands. The risk is forecast to increase to high
around Sunday into early next week. For additional information and
location-specific rip current details, please visit:
weather.gov/beach/sju.

&&

.FIRE WEATHER...
Issued at 1015 AM AST Tue Mar 10 2026

The KBDI remains above critical fire weather thresholds in Cabo
Rojo (669) and below thresholds in Guanica (519) and Camp
Santiago (383). Breezy to windy easterly winds will continue
between 14 to 19 mph with higher gusts up to 30 mph. Today, RH
values will drop near and below critical levels at times as a
patch of drier air filters into the area by mid-morning. Passing
showers will continue to move across the area from time to time;
however, drying soils, lower humidity later in the day and and
strong winds will maintain a moderate fire danger risk today. From
Wednesday onwards, winds are expected to become more light to
moderate and RH are expected increase due to the arrival of a
surge of moisture. At this time an RFD will not be issued. We
urge partners to continue monitoring updates during the morning
for a possible elevated fire danger risk if conditions warrant.

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...None.
VI...None.
AM...Small Craft Advisory until noon AST Wednesday for AMZ711.

&&

$$

SHORT TERM/AVIATION...DS
LONG TERM...LIS
MARINE/BEACH FORECAST...YZR

NWS SJU Office Area Forecast Discussion