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362
FXCA62 TJSJ 220700
AFDSJU

Area Forecast Discussion
National Weather Service San Juan PR
300 AM AST Mon Jun 22 2026

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

.KEY MESSAGES...
Issued at 300 AM AST Mon Jun 22 2026

* Dangerous heat index values will prevail today, especially
  between 10 AM and 5 PM, as hot temperatures combine with
  tropical moisture across coastal and urban areas in PR and the
  USVI. Thus, a Heat Advisory is in effect due to the possible
  heat-related illnesses without adequate hydration, cooling, and
  frequent breaks from the heat.

* Moderate concentrations of Saharan dust will filter across the
  islands once again today, resulting in hazy skies, reduced
  visibility, and degraded air quality, particularly for sensitive
  groups. Another pulse of SAL will arrive from Thursday onward.

* A weak tropical wave will move near the region between
  Wednesday and Thursday, bringing an additional chance for
  showers and thunderstorms. Forecast details will continue to be
  refined as confidence increases.

* Life-threatening rip currents will remain possible at exposed
  beaches through much of the week due to persistent moderate to
  locally breezy winds. Beachgoers should swim near lifeguards,
  heed warning flags, and follow local beach safety guidance. St
  Croix could have a high risk between Wednesday and Thursday due
  to these increasing winds.

&&

.Short Term(Today through Wednesday)...
Issued at 300 AM AST Mon Jun 22 2026

Overnight, we had little or no rain as a Saharan Air Layer
arrived, creating somewhat dry conditions and hazy skies. As we
wrote the discussion, the local mesonet reported temperatures in
the low 80s at most coastal sites in the USVI and PR, with some
regions along the north coast of PR in the mid or upper 70s.
Meanwhile, along the mountains, we observed values from the mid-
to upper 60s to the mid-70s Fahrenheit. Most wind stations
reported east-to-east-southeast winds around 10 mph or lower, with
fluctuations due to land breezes. Meanwhile, some stations in
Culebra, St. Thomas, and St. John reported east to east-northeast
winds around 15, with higher gusts.

As yesterday`s tropical wave moves farther into the central and
western Caribbean, a Saharan Air Layer (SAL) will spread across
the region, limiting rainfall while contributing to hazy skies,
reduced visibility, and degraded air quality. Although dust
concentrations are expected to decrease somewhat by Tuesday,
traces of suspended dust will likely linger across the local
islands. Meanwhile, a mid-level ridge will promote a generally
stable pattern with subsidence aloft. At the surface, a
strengthening Atlantic high-pressure system will tighten the local
pressure gradient, supporting occasional moderate to locally
breezy east-to-east-southeast winds. Within this flow, patches of
moisture will continue to bring passing showers to windward and
eastern areas, while leeward sections experience mostly fair
weather. Limited afternoon convection cannot be ruled out,
particularly across western Puerto Rico. Seasonably warm
conditions will persist, with daytime highs generally reaching the
upper 80s to lower 90s across coastal and urban areas, and
possible dangerous heat indices each day.

By Wednesday, the leading edge of a tropical wave will bring a
modest increase in low-level moisture, with total precipitable
water (TPW) values rising to near climatological normals for late
June, around 1.65 inches. As moisture increases, the frequency of
passing showers is expected to rise across the region,
particularly across windward areas. While widespread hazardous
weather is not anticipated at this time, isolated thunderstorms
and locally heavy downpours cannot be ruled out.

&&

.Long Term(Thursday through Monday)...
Issued at 300 AM AST Mon Jun 22 2026

Mostly stable weather conditions are expected through the long-term
period. While a tropical wave will pass south of the local islands
on Thursday, the deepest moisture associated with the system is
forecast to remain south of the area. A broad dry air mass will
dominate the region, with precipitable water and relative humidity
values remaining below normals. As a result, shower activity will be
limited to brief trade-wind showers across windward and eastern
areas during the overnight and morning hours, followed by isolated
afternoon convection over portions of western Puerto Rico.
Significant rainfall accumulations and flooding impacts are not
anticipated.

Moderate to potentially high concentrations of Saharan dust are
expected from Thursday through at least Saturday, promoting hazy
skies and periods of reduced visibility. The driest day of the long-
term period will be Friday. Individuals with respiratory
sensitivities should consider limiting prolonged outdoor activities
and following guidance from local health officials.

From Friday through Sunday, fair weather conditions will prevail
across most of the region, with only isolated passing showers
expected. Temperatures will remain near seasonal levels, while haze
and localized reductions in visibility associated with Saharan dust
remain the primary weather impacts through the end of the forecast
period.

&&

.AVIATION...
(06Z TAFS)
Issued at 300 AM AST Mon Jun 22 2026

A SAL will filter once again across the region, affecting
visibilities across portions of the local flying area. Thus,
expect HZ with VSBY dropping to near 6 SM, limited SHRA/-SHRA
activity, without ruling them out across windward terminals. SHRA
will form along the Cordillera and W-PR by 22/16-22z. Winds will
be calm to light and variable overnight, and after 22/13z, expect
E-ESE winds at 10-20 kt, with gusts up to 30 kt, and sea breezes.

&&

.MARINE...
Issued at 300 AM AST Mon Jun 22 2026

A broad surface high pressure system over the central Atlantic will
maintain moderate to fresh easterly to east-southeasterly winds
through the next several days, resulting in choppy seas across most
of the local waters. Therefore, small craft should exercise caution.
In addition, moderate to occasionally high concentrations of Saharan
dust will persist into later tonight, producing hazy skies, reduced
visibility, and poor air quality.

&&

.BEACH FORECAST...
Issued at 300 AM AST Mon Jun 22 2026

A moderate risk of rip currents remains in effect for most local
beaches, including northern and eastern Puerto Rico, Vieques,
Culebra, and portions of the U.S. Virgin Islands, while a low risk
persists for the south-central and western coasts of Puerto Rico and
the northern U.S. Virgin Islands. Life-threatening rip currents
remain possible.

Meanwhile, moderate to high concentrations of Saharan dust will
persist across the region through later tonight, resulting in hazy
skies, reduced visibility, and poor air quality.

&&

.FIRE WEATHER...
Issued at 300 AM AST Mon Jun 22 2026

A Fire Danger Statement has been issued for today across portions
of the coastal plains and hills of southern and western Puerto
Rico, Vieques and St. Croix due to the combination of critically
dry fuels, sustained winds of 15 to 20 mph with gusts up to 30
mph, and minimum relative humidity values in the low 50s or even
in the 40s. These conditions will favor rapid wildfire ignition
and extreme fire behavior, meaning any fires that develop will
likely spread quickly and become difficult to contain. Outdoor
burning is highly discouraged.

&&

.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.
&&

$$

KEY MESSAGES/SHORT TERM/AVIATION/FIRE WEATHER...CAM
LONG TERM....MMC
MARINE/BEACH FORECAST...ICP

NWS SJU Office Area Forecast Discussion