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921
FXCA62 TJSJ 070753 CCA
AFDSJU

Area Forecast Discussion...CORRECTED
National Weather Service San Juan PR
353 AM AST Tue Jul 7 2026

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

.KEY MESSAGES...
Issued at 134 AM AST Tue Jul 7 2026

* Dangerous heat will remain the primary weather hazard through
  the end of the workweek. A Heat Advisory is in effect today, and
  additional advisories may be needed later this week. Heat-
  related illnesses are possible without proper hydration,
  cooling, and frequent breaks.

* A fast-moving tropical wave will bring the best chance for
  showers and isolated thunderstorms on Wednesday. Ponding of
  water on roads, localized flooding, and dangerous cloud-to-
  ground lightning will be possible.

* Saharan dust will continue to degrade air quality and reduce
  visibility through much of the week, with only a brief
  improvement on Wednesday.

* Breezy easterly trade winds will maintain hazardous marine and
  beach conditions, including a moderate risk of rip currents at
  many local beaches.


&&

.Short Term(Today through Thursday)...
Issued at 134 AM AST Tue Jul 7 2026

Extensive high-level cloudiness associated with an upper-level
low northwest of the region continued streaming northeastward
across the islands, limiting nocturnal cooling. Many coastal
locations, along with a few inland sites, only fell to around 80
to 82 degrees, providing little overnight relief and increasing
heat stress, especially for those without adequate cooling.

Today, breezy easterly trade winds will continue to bring a few
passing showers across windward areas, with only a very localized
afternoon shower possible over western Puerto Rico. However,
moderate to high concentrations of Saharan dust and persistent
dry mid-level air will continue to suppress significant rainfall
while maintaining hazy skies and degraded air quality. Afternoon
temperatures in the upper 80s to lower 90s, combined with typical
to above-normal low-level moisture, will produce dangerous heat
indices. Consequently, another Heat Advisory has been issued from
10 AM to 5 PM AST for lower elevations, coastal and urban areas of
Puerto Rico, including Vieques and Culebra, as well as the U.S.
Virgin Islands. Heat-related impacts will remain the primary
weather hazard.

The axis of a fast-moving tropical wave is forecast to cross the
region tonight, with deeper moisture spreading over the islands on
Wednesday. As a result, scattered showers and isolated
thunderstorms will become more common than in recent days.
Ponding of water on roads and in poorly drained areas will be
possible, while the potential for urban and small-stream flooding
will remain limited. Frequent lightning will accompany the
strongest thunderstorms. Warm conditions will persist, although
increased cloud cover and lower Saharan dust concentrations should
make dangerous heat less widespread.

By Wednesday night into Thursday, another surge of much drier air
and Saharan dust will quickly overspread the region, returning a
hot, very dry, and hazy weather pattern with little to no rainfall
expected. Dangerous heat will once again become the primary
weather hazard, and this pattern is expected to persist through
the end of the workweek.


&&

.Long Term(Friday through Tuesday)...
Issued at 134 AM AST Tue Jul 7 2026

Dry and mostly stable conditions are expected through the upcoming
weekend and into early next week. A surface high north of the
region will maintain generally east to east-southeasterly winds,
with a brief shift to the northeast possible on Sunday due to an
induced surface trough. Another surface high over the central Atlantic
will strengthen the easterly flow again by early next week.

A drier air mass and moderate to high concentrations of Saharan
dust will continue filtering into the region, limiting shower
activity. Both the GFS and ECMWF indicate precipitable water
values falling below climatological normals through the weekend,
while forecast soundings show an unusually dry lower atmosphere.
Although an upper-level low may linger nearby, the environment
should remain unfavorable for sustained convection. Any showers
that develop will be brief, fast-moving, and produce minimal
impacts.

Hazy skies, reduced visibility, and degraded air quality will
persist as Saharan dust continues across the region. Meanwhile,
above-normal temperatures and sufficient low-level moisture will
maintain dangerous heat, with heat indices likely exceeding 102F
across urban, coastal, and lower-elevation areas. Warm overnight
temperatures will provide little relief, allowing cumulative heat
stress to persist into early next week.


&&

.AVIATION...
(06Z TAFS)
Issued at 134 AM AST Tue Jul 7 2026

VFR conditions will prevail at all TAF sites. Moderate to locally
high concentrations of Saharan dust will continue to produce HZ
and occasional VIS reductions, gradually improving overnight ahead
of an approaching tropical wave. Brief VCSH are possible near TJSJ
and TJBQ between 07/16-22Z, then near TJSJ and the USVI terminals
after 07/22Z. E-ESE winds will increase from 6-12 kt to 16-22 kt
with higher gusts between 07/13-22Z, diminishing to 8-14 kt after
07/22Z.


&&

.MARINE...
Issued at 134 AM AST Tue Jul 7 2026

A broad surface high pressure over the central Atlantic will
maintain moderate to fresh east to east-southeast winds and choppy
seas through the end of the workweek. A fast-moving tropical wave
will briefly increase showers and isolated thunderstorms late
tonight into Wednesday before drier, dustier conditions return by
Wednesday night. Moderate to high concentrations of Saharan dust
will continue to produce hazy skies and occasional visibility
reductions.


&&

.BEACH FORECAST...
Issued at 134 AM AST Tue Jul 7 2026

A moderate risk of rip currents will persist at most local beaches
through the end of the workweek as persistent moderate to fresh
easterly winds maintain hazardous surf conditions. Life-
threatening rip currents can still occur at beaches with a low
risk, especially near jetties, piers, groins, and reefs.

Dangerous heat will continue each afternoon, increasing the risk
of heat-related illnesses for beachgoers. A few thunderstorms may
develop on Wednesday as a tropical wave moves across the region.
If thunder roars, go indoors. Seek shade often, stay hydrated, and
avoid prolonged sun exposure during the hottest part of the day.


&&

.FIRE WEATHER...
Issued at 134 AM AST Tue Jul 7 2026

Higher humidity and a passing tropical wave will make weather
conditions less supportive of rapid wildfire growth through
Wednesday. Nevertheless, critically dry vegetation and persistent
soil moisture deficits will continue to favor wildfire
development, and any ignition could still spread through the
available fine fuels despite fire weather thresholds not being
met. As drier air and Saharan dust return late Wednesday into
Thursday, weather conditions will once again become more favorable
for wildfire growth through the end of the workweek. Residents and
visitors should avoid outdoor burning and use extreme caution with
any activity capable of producing sparks or open flames.


&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...Heat Advisory from 10 AM this morning to 5 PM AST this afternoon
     for PRZ001>005-007-008-010>013.

VI...Heat Advisory from 10 AM this morning to 5 PM AST this afternoon
     for VIZ001-002.

AM...None.
&&

$$

EVE...GRS/MNG
MID...ICP

NWS SJU Office Area Forecast Discussion