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

879
FXCA62 TJSJ 081848
AFDSJU

Area Forecast Discussion
National Weather Service San Juan PR
248 PM AST Thu Oct 8 2026

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

.KEY MESSAGES...
Issued at 241 PM AST Thu Oct 8 2026

- Excessive heat will remain a concern over the next several
  days, as warm temperatures and elevated heat indices increase
  the risk of heat-related illnesses.

- An increase in atmospheric instability is forecast from late
  Sunday into the upcoming workweek, increasing the potential for
  flooding and lightning across the region throughout much of the
  long-term period.

- For the U.S. Virgin Islands, excessive heat will be the primary
  threat over the next two days.

&&

.Short Term(This evening through Saturday)...
Issued at 241 PM AST Thu Oct 8 2026

Passing showers moved across portions of the U.S.
Virgin Islands and eastern Puerto Rico during the morning hours,
driven by an east-southeast wind flow and lingering moisture from a
distant tropical wave well to the west. By noon, the San Juan
streamer began to develop, affecting portions of San Juan, Guaynabo,
and Catano. Doppler-radar-estimated rainfall accumulations of up to
0.60 inches. Maximum temperatures remained in the upper 80s to low
90s across coastal and urban areas, while the central mountain range
of Puerto Rico reached the low 80s. Winds prevailed mainly from the
east-southeast at 10 to 15 mph, with higher gusts and sea breeze
variations.

For the rest of the afternoon and into the evening, abundant
tropical moisture combined with daytime heating and local effects
will bring showers and thunderstorms to central, western, and
northwestern Puerto Rico. Because recent rains have already
saturated the soil, any additional rainfall could trigger urban and
small-stream flooding, quick river rises, and landslides,
particularly across northwestern Puerto Rico. Additional showers
could also develop across the San Juan metropolitan area. Shower and
thunderstorm activity will diminish before sunset, moving into a
calmer, more stable night.

Weather conditions will gradually improve on Friday as drier air
filters over the islands, bringing precipitable water (PWAT) values
below normal to around 1.50 inches alongside mid- to upper-level
ridging. As the surface high-pressure system over the central
Atlantic migrates eastward, winds will shift to the east in the
morning and east-northeast by the afternoon, bringing slightly
cooler temperatures and breezy conditions. Under this pattern,
daytime heating and local effects will spark afternoon showers and
isolated thunderstorms across central, western, and southwestern
Puerto Rico.

By Saturday, conditions will transition back to a wetter pattern as
an upper-level low positions east of the islands, increasing
instability aloft and raising the potential for thunderstorms across
the region. Although the overall heat risk will remain limited over
the next few days, warm temperatures will persist, and residents and
visitors are encouraged to stay hydrated and seek shade during peak
afternoon heat.

&&

.Long Term(Sunday through next Wednesday)...
Issued at 241 PM AST Thu Oct 8 2026

An upper-level low is forecast to meander over the region through
the long term forecast. This will cause unstable conditions aloft as
500 mb temperatures drop to -7/8 degrees Celsius through most of the
period. This cooling aloft will produce steep mid-level lapse rates
and in addition, a 250 mb jet will provide strong upper-level
divergence and ventilation that can support deep, organized
convection each day. At the surface, moderate to locally fresh
trades are expected through Monday as a surface high pressure moves
over the western Atlantic and an induced low-level trough moves from
east to west across the islands. Lighter ESE winds are expected
thereafter through midweek.

A gradual pooling of moisture is expected across the eastern
Caribbean as the low moves south of the islands and winds veer from
southeast. Precipitable water content is expected to range between
1.75-2.10 inches through the forecast period. A saturated
atmospheric column with deep instability and strong upper-level lift
can produce multiple rounds of heavy showers and intense
thunderstorms. Consequently, there will be an elevated threat of
urban and small-stream flooding, localized flash flooding, strong
gusty winds, and frequent lightning. While daytime heating and local
effects will still focus the most intense, slow-moving convection
over the interior and western portions of Puerto Rico, the broad
synoptic forcing will also bring periods of locally heavy rainfall
and strong thunderstorms to the USVI and eastern PR.&&

.AVIATION...
(18Z TAFS)
Issued at 241 PM AST Thu Oct 8 2026

Aftn SHRA/TSRA will continue to develop and spread across
portions of interior PR to W-NW PR thru 08/23Z. Brief MVFR/IFR
conds are possible in heavier SHRA/TSRA, along with mtn obsc,
particularly at TJBQ from around 08/19-08/21Z. Additional SHRA
will result in VCSH/-SHRA at TJSJ & TJPS thru 08/22Z. Locally
reduced VSBY, LTG, lower CIGs and gusty/VRB winds possible. ESE
winds 10-15 kt thru 08/00Z, becoming light/VRB overnight an
increasing again at 09/14Z from the E.

&&

.MARINE...
Issued at 241 PM AST Thu Oct 8 2026

A broad surface high-pressure system over the central Atlantic, in
combination with a stationary frontal boundary over the western
Atlantic, will continue to promote a southeasterly wind flow
across the region. This pattern will result in moderate
southeasterly winds of up to 15 knots, with seas reaching up to 5
feet across the offshore Atlantic and Caribbean waters. Elsewhere,
seas will generally range between 2 and 3 feet across the local
waters. As the surface high-pressure system strengthens over the
central Atlantic, moderate winds are expected to persist from
Friday through Sunday.


.BEACH FORECAST
... Issued at 241 PM AST Thu Oct 8 2026

A moderate risk of rip currents will persist through the rest of
the evening along the northern and northeastern coasts of Puerto
Rico, Culebra, Vieques, and St. Thomas. Conditions are expected to
improve later this evening and into the weekend, with the rip
current risk diminishing to low and remaining low through Sunday.
Although marine conditions will generally be favorable, breezy
conditions may result in locally choppy seas, particularly in
exposed coastal areas. Despite the low rip current risk,
beachgoers should remain alert for other beach hazards, including
lightning associated with strong thunderstorms during the
afternoon hours.&&

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

$$

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

NWS SJU Office Area Forecast Discussion