Your Number One Source for Real-Time Puerto Rico Weather & Hurricane Tracking Updates

192
FXCA62 TJSJ 091806
AFDSJU

Area Forecast Discussion
National Weather Service San Juan PR
206 PM AST Fri Oct 9 2026

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

.KEY MESSAGES...
Issued at 203 PM AST Fri Oct 9 2026

 * A limited to elevated flooding threat is expected for tomorrow
   along western and southwestern PR.

 * A limited heat threat is expected for the upcoming days during
   the weekend.

 * An increase in instability is expected as an upper-level low moves
   over the region, increasing the flood and lightning threat
   from Monday into Wednesday.

 * There is a low risk of rip currents across all the coastal
   areas.

&&

.Short Term(This evening through Sunday)...
Issued at 203 PM AST Fri Oct 9 2026

A tranquil weather pattern was observed during the morning hours
today, with little to no cloudiness or shower activity across the
islands. Satellite imagery showed mostly clear skies until around
11 AM AST, when clouds began to develop, followed by showers along
the Cordillera Central. By 1 PM AST, showers had increased in
frequency and coverage, with streamers extending from Culebra and
Vieques into mainland Puerto Rico and moving westward under the
easterly wind flow. Showers were more significant across the
western interior, with rainfall accumulations remaining below one
inch due to their rapid movement. Daytime temperatures were in the
low 90s across coastal areas and portions of the western interior
and in the low 80s across mountainous areas.

For the rest of the evening, relatively dry conditions will favor
limited shower activity and cloudiness across the islands.
However, a few passing showers may affect eastern Puerto Rico and
the U.S. Virgin Islands as moisture gradually increases overnight.
On Saturday, east to northeast winds will prevail as an induced
surface perturbation moves over the region and supports increasing
moisture. According to the latest GFS guidance, precipitable water
will rise to around 2.1 inches Saturday morning, near the 75th
climatological percentile, while relative humidity increases
through the lower and middle levels. This moisture will favor
passing morning showers across windward coastal areas, followed by
afternoon development across western and southwestern Puerto Rico
due to daytime heating and local effects. Locally heavy showers
may result in ponding of water on roads and in poorly drained
areas. However, limit thunderstorm development is expected, with a
limited lightning threat associated with the strongest
convection. Moisture will gradually decrease later Saturday,
favoring a reduction in shower coverage during the evening. Heat
threat is not expected to pose a significant threat across most of
the region, as easterly winds and decreasing low-level
temperatures will favor more seasonable conditions and heat
indices generally below 108F.

On Sunday, a broad surface high-pressure system over the western
Atlantic will maintain easterly surface winds as an easterly wave
approaches the region. Precipitable water values will fluctuate
between approximately 1.8 and 1.9 inches through the morning
before decreasing later in the day. Available moisture will
support passing showers across eastern Puerto Rico and the U.S.
Virgin Islands, followed by afternoon convection over interior and
western Puerto Rico. GFS guidance indicates falling upper-level
heights and cooling temperatures at 500 mb to around 7C. These
will suggest a more favorable environment for deeper convection,
particularly as the upper-level feature moves closer to the
region. The combination of available moisture, daytime heating,
and local effects will support showers and isolated thunderstorms,
with localized ponding of water and lightning possible with the
strongest activity.

&&

.Long Term(Monday through next Thursday)...
Issued at 203 PM AST Fri Oct 9 2026

A strong upper-level low will be the dominant feature throughout the
period. Associated instability will drive 500 mb temperatures below
9 degrees Celsius on Monday and maintain values below -7 degrees
Celsius through midweek, causing steep mid-level lapse rates. This
setup, combined with seasonal PWAT values around 1.85 to 2.10
inches, daytime heating, and local effects, will support deep,
organized convection each day. Furthermore, as the upper-level low
tracks south of the islands, it will continue to deepen moisture
through the atmospheric column.

On Monday and Tuesday, light-to-moderate easterly flow will steer
slow-moving showers and thunderstorms, primarily focusing activity
over the interior to western sections of Puerto Rico. For the
remainder of the period, winds will shift more east-southeasterly
and strengthen, shifting the convection to the interior and
northwestern Puerto Rico. Regardless, passing showers and
thunderstorm activity cannot be ruled out across eastern Puerto Rico
and the USVI each day.

These conditions will maintain a risk of urban and small stream
flooding, with flash flooding possibleparticularly on Monday, when
lighter winds will favor slow-moving showers with higher rainfall
accumulations. In addition, localized strong wind gusts and frequent
lightning are expected with the strongest thunderstorms.&&

.AVIATION...
(18Z TAFS)
Issued at 203 PM AST Fri Oct 9 2026

Mainly VFR conds will continue across all TAF sites during the
forecast period. Aftn SHRA/TSRA will develop across the central
mountain range and move over portions of the interior to W-SW PR,
affecting mostly TJPS thru 09/23Z. Additional SHRA will result in
VCSH/-SHRA at TJSJ/TIST/TISX thru 09/23Z. E winds 15-20 kt with
higher gusts and seas breeze variations thru 09/23Z, becoming
light/VRB overnight.

&&

.MARINE...
Issued at 203 PM AST Fri Oct 9 2026

A weak surface high pressure over the central Atlantic will continue
to drift eastward and displaced by a frontal boundary moving east
across the western Atlantic. This will continue to result in weak
pressure gradient, maintaining mainly gentle to moderate easterly
trade winds. Another surface high-pressure will build across the
western Atlantic over the weekend, sustaining moderate to locally
fresh easterly trade winds. An induced surface trough will move near
the region from Saturday onwards, promoting an increase in showers
and thunderstorms across the local waters.

&&

.BEACH FORECAST...
Issued at 203 PM AST Fri Oct 9 2026

A low risk of rip currents will continue across all beaches of
Puerto Rico, Vieques, Culebra and the U.S. Virgin Islands through
early next week. Although the risk is low, beachgoers are encouraged
to pay attention to beach conditions as life-threatening rip current
can occur in the vicinity of jetties, piers, reefs, and groins. In
addition, beachgoers must remain weather alert, as shower and
thunderstorm activity is expected each day, particularly near the
western coastal areas of the islands.

&&

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

$$

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

NWS SJU Office Area Forecast Discussion