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

226
FXCA62 TJSJ 300729
AFDSJU

Area Forecast Discussion
National Weather Service San Juan PR
329 AM AST Tue Jun 30 2026

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

.KEY MESSAGES...
Issued at 321 AM AST Tue Jun 30 2026

* Moderate to high concentrations of Saharan Dust will continue to
  filter across Puerto Rico and the U.S. Virgin Islands today,
  resulting in hazy skies, reduced visibility, and poor air
  quality. Sensitive groups must follow medical recommendations.

* Limited shower activity is expected across the islands today,
  however, localized afternoon showers and few isolated
  thunderstorms are possible across northwestern Puerto Rico.

* Warmer to hot conditions are expected for the next few days,
  with heat indices reaching or exceeding 105 degrees Fahrenheit
  across urban and low-lying areas of Puerto Rico and the U.S.
  Virgin Islands. Stay hydrated!

&&

.Short Term(Today through Thursday)...
Issued at 321 AM AST Tue Jun 30 2026

Calm and quiet conditions prevailed overnight across Puerto Rico and
the U.S. Virgin Islands under mostly clear to partly cloudy skies. A
few isolated showers developed across the region but remained over
the coastal waters. Overnight lows ranged from the upper 70s to low
80s in urban and coastal areas, and from the upper 60s to low 70s in
the mountains. Winds were light and variable at 5 knots or less.

Today, moderate to high concentrations of Saharan dust will
continue to filter into the islands, causing hazy skies, reduced
visibility, and poor air quality. While these conditions will
generally suppress rainfall, patches of moisture and a tropical
wave moving south of the area will still trigger fast-moving,
passing showers across the islands. Residents and visitors,
particularly sensitive groups, including individuals with
respiratory conditions, are urged to limit prolonged outdoor
exposure and take necessary precautions.

A broad high-pressure system and a strengthening mid-level ridge
will continue to maintain relatively drier conditions aloft,
inhibiting the development of strong showers and limiting
thunderstorms through Thursday. Under this pattern, passing showers
will impact portions of eastern Puerto Rico and the U.S. Virgin
Islands during the morning hours, followed by locally induced
afternoon showers and thunderstorms across western and northwestern
Puerto Rico.

Over the next few days, warm temperatures will persist, rising into
the upper 80s and low 90s across coastal and urban areas, and into
the low to mid-80s in the mountains. Heat indices are forecast to
reach or exceed 105-111F, particularly during the peak heating
hours of the day. Everyone is urged to practice heat safety by
staying hydrated, limiting strenuous outdoor activities, and taking
frequent breaks in shaded or air-conditioned areas.

&&

.Long Term(Friday through Tuesday)...
Issued at 321 AM AST Tue Jun 30 2026

The long-term forecast remains on track. A transition from a
relatively dry and hazy air mass to a highly saturated and unstable
tropical environment is anticipated across the local area. At the
surface, a dominant high pressure system over the Central Atlantic
will maintain the local pattern under southeasterly winds,
fluctuating at times, particularly during the morning hours. Aloft,
a 250 mb cut-off low will remain anchored near the region throughout
the entire forecast period, providing continuous upper-level support
and maintaining a marginally unstable environment with 500 mb
temperatures forecast to range between -8 C and -7 C. From Friday
into Saturday, despite the instability aloft, available moisture
will remain relatively shallow and trapped below the 850 mb level.
The NASA Goddard aerosol model guidance again indicates a mass of
Saharan dust moving across the region, which will promote hazy skies
and effectively suppress widespread convective activity.
Consequently, residents can expect a variable weather pattern
characterized by hot conditions and limited rainfall accumulations,
though brief morning showers across eastern Puerto Rico and isolated
afternoon convection over the western interior and northwestern
sectors cannot be entirely ruled out due to local effects and
daytime heating.

From Sunday into Tuesday, the latest global model guidance from both
the ECMWF and GFS indicates an increase in mid-level moisture, with
increasing relative humidity values at the 700 mb level arriving in
the region. This will enhance a variable weather pattern, boosting
the development of afternoon convection across the western and
northwestern interior of Puerto Rico. Meanwhile, Saharan dust
concentrations will gradually diminish, allowing low-level moisture
to become more uniform by Monday. By Tuesday, a significant increase
in deeper atmospheric moisture is highly anticipated across the
northeastern Caribbean as a tropical wave approaches and moves
through the local area. The arrival of tropical moisture, combined
with the favorable upper-level dynamics provided by the persistent
cut-off low, will erode any remaining stable layers and allow
precipitable water values to expand well above normal levels. This
interaction will result in an increase in widespread shower and
isolated thunderstorm activity across the region, bringing a limited
to elevated potential for localized ponding of water on roadways and
in poorly drained areas. Regardless of the changing moisture levels,
persistently warm conditions will dominate coastal and urban sectors
for the entirety of the long-term period. An elevated heat threat
will remain present each day, with maximum heat index values
consistently peaking between 100 and 108 F across portions of the
north-central coastal plain and southern Puerto Rico during the peak
heating hours.

&&

.AVIATION...
(06Z TAFS)
Issued at 321 AM AST Tue Jun 30 2026

VFR conds are expected to prevail across all TAF sites. Afternoon
SHRA may result in VCSH at TJBQ & TJSJ btw 30/17-23Z. SE winds
between 12-16 kt are expected with higher gusts and sea breeze
variations. Winds will become light and variable at 5-10 kt aft
30/23Z.

&&

.MARINE...
Issued at 321 AM AST Tue Jun 30 2026

The surface high pressure across the Central Atlantic as well as a
frontal low over the western Atlantic will promote moderate to
locally fresh east to east-southeasterly winds causing moderate
chops or even choppy seas. Therefore, small craft should exercise
caution. A dense Saharan Air Layer will deteriorate air quality on
through tomorrow; additional concentrations are forecast to start to
filter in on Friday and during the weekend.

&&

.BEACH FORECAST...
Issued at 321 AM AST Tue Jun 30 2026

Throughout the rest of the workweek, most beaches across Puerto Rico
and the U.S. Virgin Islands should remain with a low risk of rip
currents. However, life-threatening rip currents often occur in the
vicinity of groins, jetties, reefs, and piers. Only localized areas
under a moderate risk of rip currents (rip currents are possible in
the surf zone) are possible this workweek. The moderate risk should
gradually spread to other beaches by the upcoming weekend, as the
local pressure gradient increases and winds strengthen, with a
moderate risk of rip currents across most beaches of the islands.
Moderate to high concentrations of Saharan Dust will continue to
gradually filter into the region, persisting through tomorrow,
Wednesday; additional concentrations are forecast to start to filter
in on Friday and during the weekend. These concentrations will
result in hazy skies, reduced visibility, and poor air quality. High
Heat Indices will continue during the next several days.

&&

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

$$

SHORT TERM...GRS
LONG TERM....LIS
MARINE/BEACH...MRR

NWS SJU Office Area Forecast Discussion