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

330
FXCA62 TJSJ 270738
AFDSJU

Area Forecast Discussion
National Weather Service San Juan PR
338 AM AST Sat Jun 27 2026

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

.KEY MESSAGES...
Issued at 329 AM AST Sat Jun 27 2026

* A surface trough will move over the islands this morning,
  increasing moisture and shower activity. Winds will gradually
  veer during the morning as the trough axis moves westward,
  starting from the ENE and then becoming ESE by this afternoon.

* This flow will promote showers and isolated t-storms over interior
  to NW PR this afternoon, as well as lines of showers from El
  Yunque and the local islands, increasing the flooding risk.

* Warm weather conditions should prevail across the islands during
  the next several days, generating up to an elevated heat threat.

* Although drier conditions are expected on Sunday, an approaching
  tropical wave will once again increase moisture and flooding
  risk on Monday.

&&

.Short Term(Today through Monday)...
Issued at 329 AM AST Sat Jun 27 2026

Shower frequency increased across most of the region overnight due
to an approaching surface trough. This system is expected to cross
the islands this morning, sustaining elevated moisture levels and
shower activity. Precipitable water (PWAT) values are forecast to
remain within normal ranges (up to approximately 1.9 inches),
potentially reaching slightly above-normal levels during this
afternoon`s convection. As the trough axis shifts westward,
morning winds will gradually veer from the ENE to the ESE by this
afternoon. While 925 mb wind speeds may decrease slightly, they
will remain within seasonal norms. This ESE steering flow will
direct showers toward windward sectors, as well as triggering
convective showers and isolated t-storms over interior and W-NW
Puerto Rico later today. Additionally, lines of showers can form
off El Yunque and the local islands. These conditions will elevate
the risk of flooding, resulting in possible urban and small stream
flooding, as well as water ponding on roadways and in areas with
poor drainage.

A drier air mass is expected to reach the area late tonight and
Sunday, resulting in a more typical dry weather pattern with low
concentrations of Saharan Dust. Residents can anticipate morning
showers in windward sectors, followed by isolated afternoon
convective showers across interior and W-NW Puerto Rico. ESE
breezes will also reintroduce a low concentration of Saharan dust
to the area. Current guidance indicates that a tropical wave, its
associated moisture field and an approaching upper trough will
affect the region on Monday, leading to a notable rise in deep-
layer moisture over the local islands. Consequently, precipitable
water (PWAT) levels are expected to climb to above normal values
while 500 mb temperatures cool to more normal values, providing
further support for convective activity during the afternoon
hours. Furthermore, relative humidity and lapse rates in the
700-500 mb layer is projected to exceed seasonal norms. This surge
in moisture will again increase the flooding risk and can result
in more widespread showers and t-storms as well as afternoon
convection over interior to western and northwestern Puerto Rico
as well as downwind of the local islands and El Yunque. Localized
water ponding as well as flooding can occur on roads and in areas
with poor drainage. An elevated heat risk will persist during the
period as 925 mb temperatures are forecast at above normal values
each late morning to afternoon. This level of heat affects most
individuals sensitive to heat, especially those without effective
cooling and/or adequate hydration.

&&

.Long Term(Tuesday through Saturday)...
Issued at 329 AM AST Sat Jun 27 2026

During the long-term period, a surface high pressure system centered
over the central Atlantic and extending into the Caribbean will
maintain a southeasterly low-level wind flow (03 km) across Puerto
Rico and the U.S. Virgin Islands. Aloft, nearly zonal flow at 200 mb
is expected on Tuesday and Wednesday, providing little in the way of
upper-level support for organized convection. Lingering moisture
associated with the previous tropical wave will remain over the
region on Tuesday, with precipitable water values around 1.8 inches
supporting scattered showers, primarily during the afternoon across
western and interior Puerto Rico. Although moisture will gradually
decrease by Thursday, sufficient low-level moisture will remain to
support isolated to scattered afternoon convection, but widespread
rainfall activity is not anticipated. Meanwhile, a moderate
concentration of Saharan dust is expected to spread across the
islands Tuesday and Wednesday, resulting in hazy skies and limiting
overall convective development.

Despite the presence of Saharan dust, the persistent southeasterly
flow will continue to promote a warm pattern, with above-normal
temperatures and elevated heat indices across urban and coastal
sections. Consequently, an elevated heat threat is expected to
persist through the middle of the week. By Friday into Saturday, a
drier air mass will move into the region, reducing precipitable
water values and limiting shower activity across the local islands.
In addition, the NASA Goddard Earth Observing System (GEOS) Model V5
continues to suggest another pulse of Saharan dust arriving late
Friday into Saturday, reinforcing the drier pattern while
maintaining hazy skies.

&&

.AVIATION...
(06Z TAFS)
Issued at 329 AM AST Sat Jun 27 2026

Mainly VFR conditions. Passing -SHRA/VCSH across windward terminals
today as a surface trough moves over the islands. After 27/16Z,
-TSRA/VCTS over TJBQ and possibly over TJSJ, prompting possible
 brief MVFR conditions. Winds will gradually veer this morning as
 the trough axis moves westward, starting from the E to ENE, and
 then becoming ESE at around 12 to 17 kts with higher gusts and
 sea breeze variations; winds decreasing after 27/23Z to 5 to 12
 kts, with land breezes.

&&

.MARINE...
Issued at 329 AM AST Sat Jun 27 2026

A surface trough moving near the northeastern Caribbean will weaken
the local pressure gradient associated with the Atlantic high
pressure system. As a result, moderate east to east-northeast winds
are expected from today. The trough will also enhance shower
activity across the regional waters, with the potential for isolated
thunderstorms. By Sunday, moderate east to east-southeast winds will
return as the Atlantic high pressure system reestablishes itself.
Another tropical wave is expected to move across the region on
Monday, bringing another increase in showers and the potential for
isolated thunderstorms.

&&

.BEACH FORECAST...
Issued at 329 AM AST Sat Jun 27 2026

A low risk of rip currents is expected along most local beaches
through the weekend. However, even when the risk is low, isolated
life-threatening rip currents can still occur, especially near
jetties, groins, reefs, and piers.

A moderate rip current risk is forecast to develop for some beaches
early next week, meaning life-threatening rip currents will become
possible. Beachgoers are encouraged to swim near a lifeguard, heed
posted warning flags, and follow the guidance of local beach patrols.

Hot and humid conditions may produce dangerous heat levels at the
beaches. Stay hydrated, seek shade frequently, wear lightweight
clothing, and limit prolonged sun exposure during the hottest part
of the day.

In addition, isolated thunderstorms may develop this afternoon,
mainly across northern and western Puerto Rico. If you are at the
beach or participating in outdoor activities, remain alert for
lightning. Remember: If you can hear thunder, you are close enough
to be struck by lightning. Move to a substantial building or a hard-
top vehicle immediately and remain there until 30 minutes after the
last rumble of thunder.

&&

.FIRE WEATHER...
Issued at 329 AM AST Sat Jun 27 2026

A surface trough will move over the islands today, bringing a
moisture field that will be over the region through early tonight
and providing some relief in terms of RH values. As the trough
axis crosses the islands, winds will veer from ENE to ESE later
today. Once winds veer to become more ESE, they will increase to
10 to 20 mph, with higher gusts. This wind direction could steer
some passing showers over the region and provide some relief to
the SW coastal plains today, the SE coastal plains have been
receiving passing showers during the overnight hours. Although
low, rainfall accumulations where detected by radar yesterday
afternoon over the SW coastal plains. Nevertheless, relative
humidities in the 40s to low 50s continue to be possible at times.
Drier conditions expected tomorrow, Sunday, prompting a possible
high fire danger risk. Up to a moderate fire danger risk is
forecast today, please continue to monitor for any updates.

&&

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

$$

KEY MESSAGES...MRR
SHORT TERM...MRR
LONG TERM....LIS
AVIATION...MRR
MARINE...CAM
BEACH FORECAST...CAM
FIRE WEATHER...MRR

NWS SJU Office Area Forecast Discussion