National Weather Service Today's Weather Impact Levels

320
FXCA62 TJSJ 050701
AFDSJU

Area Forecast Discussion
National Weather Service San Juan PR
301 AM AST Sun Apr 5 2026

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

.KEY MESSAGES...
Updated at 300 AM AST Sun Apr 5 2026

* An unsettled and moist weather pattern will persist across
  Puerto Rico and the U.S. Virgin Islands through at least
  midweek, supporting an elevated to locally significant risk of
  flooding each afternoon and evening.

* Thunderstorms are expected to develop daily, producing gusty
  winds and frequent lightning.

* Breezy to locally windy conditions will continue, enhancing
  moisture transport across the region.

* Additionally, life-threatening rip currents will persist along
  the north- and east-facing beaches of the archipelagos of PR
  and the USVI.

* Warmer-than-normal temperatures will develop by midweek, with
  heat indices potentially reaching the low 100s.

&&

.Short Term(Today through Tuesday)...
Issued at 300 AM AST Sun Apr 5 2026

Fair weather prevailed today across the islands, with passing
showers over the local waters and moving inland across the
windward sections, especially across southeast PR and the USVI.
The east-southeasterly winds were mainly at 10 mph or less, with
land-breeze variations, especially along the leeward sections.
Most coastal and urban sites recorded minimum temperatures in the
low or mid-70s, while mountain sites recorded minimum temperatures
in the low 60s.

A surface high-pressure system building across the western to
central Atlantic will maintain an east-to-east-southeast wind flow
across the islands, resulting in breezy to locally windy
conditions. Embedded within this flow, patches of moisture will
continue to move across the region, promoting passing trade wind
showers across windward sectors of Puerto Rico and the U.S. Virgin
Islands during the overnight and early morning hours. By late
morning into the afternoon, diurnal heating, local sea breeze
convergence, and orographic effects will favor the development of
convection across the interior and western portions of Puerto
Rico, with activity potentially spreading into surrounding coastal
and urban areas.

A mid- to upper-level trough will enhance atmospheric instability
across the region, while model guidance indicates near- to above-
normal precipitable water values. This combination will support an
active convective pattern each day. As a result, a limited to
elevated risk of flooding rains will persist, particularly during
the afternoon and evening hours across interior, western, and
eastern Puerto Rico, as well as portions of the northern U.S.
Virgin Islands. Although periods of fair weather with partly sunny
skies are expected at times, the prevailing breezy pattern and
sustained moisture advection will maintain favorable conditions
for shower and thunderstorm development. Isolated thunderstorms
may produce frequent lightning and locally gusty winds.

&&

.Long Term(Wednesday through Sunday)...
Issued at 300 AM AST Sun Apr 5 2026

The current forecast remains on track, with a period of wet and
unstable weather across Puerto Rico and the U.S. Virgin Islands.
This pattern is driven by a mid-to-upper-level trough approaches
from the west and settles over the northeastern Caribbean. At the
surface, an induced inverted trough near Hispaniola will maintain a
persistent southeasterly wind flow, pulling deep tropical moisture
into the region. Precipitable water (PWAT) values are forecast to
reach 2.00 to 2.20 inches by Wednesday, well above climatological
normals.

Combined with above-normal temperatures at the 925 mb level, this
setup could drive heat indices into the low 100s for the first time
this year, a trend that may persist through the weekend.
Furthermore, cooler mid-level temperatures ranging from -8C to -9C
will likely enhance convective instability, leading to intense
thunderstorms and frequent lightning.

Daily widespread rainfall and thunderstorms are anticipated,
particularly during the afternoon hours across central, northern,
and northwestern Puerto Rico, including the San Juan metro area.
This activity will be enhanced by diurnal heating and local effects.
The most active period is expected on Wednesday and Thursday,
bringing a high risk of: heavy rainfall, gusty winds, frequent
lightning, rapid river rises, potential landslides and urban and
small stream flooding, especially in areas with saturated soil. In
contrast, the U.S. Virgin Islands will likely experience only
occasional passing showers with minor impacts during this timeframe.

Conditions are expected to improve by Friday as the trough weakens
and departs the area. While lingering moisture may trigger isolated
or scattered showers, the overall intensity and coverage will
diminish. From Saturday onwards, the region will transition back to
a more stable weather pattern, characterized by passing trade wind
showers and typical afternoon convection over central and western
Puerto Rico.

&&

.AVIATION...
(06Z TAFS)
Issued at 300 AM AST Sun Apr 5 2026

VFR conds will prevail, but MVFR/brief IFR may occur due to
passing SHRA/+SHRA/TSRA. Eastern terminals like TJSJ/TIST/TISX
will experience trade wind SHRA, especially in the morning and
evening. Afternoon convection will mainly affect interior and
W terminals, such as TJBQ. Winds will be calm-light/VAR until
5/13Z, then shift to ESE at 10-20 kt, with higher gusts near
convection. Be aware of mountain obscuration, reduced visibility
in heavy rain, and isolated lightning.

&&

.MARINE...
Issued at 300 AM AST Sun Apr 5 2026

Hazardous marine conditions are expected to persist through early
this week. A strong high-pressure system over the Atlantic will
maintain moderate to fresh east-southeasterly winds today, and this
pattern will persist through most of the period. When combined with
a fading northeasterly swell, seas will remain choppy to rough,
particularly across Atlantic waters and local passages. While trade
wind showers continue across the region, isolated to scattered
thunderstorms are expected, especially during the afternoon hours
over coastal waters, particularly near western and northwestern
Puerto Rico. Coverage may increase slightly throughout the week as a
series of nearby troughs interact with abundant tropical moisture.

&&

.BEACH FORECAST...
Issued at 300 AM AST Sun Apr 5 2026

A high risk of rip currents (life-threatening rip currents are
likely in the surf zone) continues for the northern and eastern
coastlines of Puerto Rico, Vieques, Culebra, and the USVI, though
conditions have begun to gradually subside. Breaking waves can still
reach to around 7 feet, particularly along the northern coastline
of Puerto Rico. This is due to a slowly fading northeasterly
swell and breezy to locally windy conditions.

Although hazards will continue to gradually diminish, a high rip
current risk will persist for most of these areas through at least
Monday. Beachgoers and inexperienced surfers are strongly urged to
stay out of the water. A moderate risk of rip currents is expected
to develop across some areas by Tuesday, with conditions becoming
more hazardous again by midweek through the end of the workweek as
another swell impacts the northern shoreline.

Beachgoers and inexperienced surfers should avoid entering the
water, especially near rocks or jetties, as life-threatening rip
currents remain possible. Heed the advice of lifeguards, beach
patrol flags, and posted signs. Access to hazardous beaches may be
limited, and individuals should follow all posted warnings and
safety guidance.

Visitors should also remain mindful of the weather in addition to
surf hazards. Passing showers and isolated thunderstorms may still
develop, particularly during the afternoon hours, producing locally
gusty winds and brief heavy rainfall. If thunder is heard, seek
shelter indoors immediately.

For additional information and location-specific rip current
details, please visit: weather.gov/beach/sju.

&&

.HYDROLOGY...
Issued at 300 AM AST Sun Apr 5 2026

An elevated risk of flooding will persist across the region
through at least midweek due to a combination of abundant
moisture, atmospheric instability, and recurrent convection. Urban
flooding, small-stream flooding, and rapid river rises are
possible each afternoon and evening, particularly across interior
and western Puerto Rico, as well as in urban and poorly drained
areas. The highest risk is expected during the midweek period,
when deeper moisture and stronger instability coincide. Localized
flash flooding and isolated landslides are also possible in areas
with steep terrain and saturated soils. Residents and visitors are
urged to remain alert to changing weather conditions and to avoid
flooded roadways.

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...High Rip Current Risk through Monday afternoon for PRZ001-002-
     005-008-012.

     High Rip Current Risk through late tonight for PRZ010-013.

VI...High Rip Current Risk through Monday afternoon for VIZ002.

     High Rip Current Risk through late tonight for VIZ001.

AM...Small Craft Advisory until 6 PM AST Monday for AMZ711.

     Small Craft Advisory until 6 AM AST Monday for AMZ712-716-741.

     Small Craft Advisory until noon AST Monday for AMZ723.

     Small Craft Advisory until noon AST today for AMZ742.

&&

$$

KEY MESSAGE/SHORT TERM/AVIATION/HYDROLOGY...CAM
LONG TERM....GRS
MARINE/BEACH FORECAST...CVB

NWS SJU Office Area Forecast Discussion