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941
FXCA62 TJSJ 081752
AFDSJU

Area Forecast Discussion
National Weather Service San Juan PR
152 PM AST Mon Jun 8 2026

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

.KEY MESSAGES...
Issued at 152 PM AST Mon Jun 8 2026

* Dangerous heat will continue through much of the week. Heat
  indices may exceed 100F, especially across urban, coastal, and
  lower-elevation areas of Puerto Rico and the U.S. Virgin
  Islands. Heat Advisories may be needed at times.

* An increase in moisture and instability is expected on
  Wednesday and Thursday, increasing the potential for showers and
  thunderstorms. The greatest impacts are expected across
  interior and western Puerto Rico during the afternoon and
  evening hours.

* Traces of Saharan dust will persist through the forecast
  period, producing somewhat hazy skies and reduced air quality,
  especially through tomorrow.

* A breezy east to east-southeast wind flow will persist through
  the period, promoting passing showers across windward areas and
  maintaining warm overnight temperatures.

* Another increase in moisture is possible Sunday into Monday,
  supporting a return to a more active pattern of passing showers
  and afternoon thunderstorms across portions of Puerto Rico and
  the U.S. Virgin Islands.

&&

.Short Term(This evening through Wednesday)...
Issued at 152 PM AST Mon Jun 8 2026

Traces of the Saharan Air Layer led to hazy skies, with a warmer-
than-normal morning, with minimum temperatures in the upper 70s or
even the low 80s at lower elevations in PR and the USVI. A patch
of moisture then brought showers across the USVI surrounding
waters and the eastern third of PR, with minimal rainfall; with
most of the activity dissipated by late morning into the
afternoon. Winds were mainly from the east-southeast at 10 to 20
mph, with higher gusts and sea-breeze variations.

Heat indices are still dangerous for the most vulnerable
communities throughout the rest of this afternoon; thus, a Heat
Advisory will remain in effect for coastal and urban areas in PR
and the USVI. However, excessive heating, along with sea breeze
variations and local effects, will promote the formation of
showers the rest of this afternoon, without ruling out one
thunderstorm (although the dry air and warmer-than-normal
temperatures aloft will limit the potential) over the interior or
northwest PR. Later this evening, expect quiet weather with
warmer-than-normal overnight hours, with a few showers arriving
across the USVI and PR windward locations.

A similar weather pattern is possible tomorrow, featuring warmer-
than-normal temperatures, dangerous heat indices, a few quick-
moving showers across windward areas, and limited afternoon
convection across western PR.

Satellite data shows a polar trough over the Western Atlantic.
Model guidance suggests this trough amplifying across the western
Atlantic, reaching the northeast Caribbean around Wednesday,
promoting better mid- and upper-level dynamics for the region.
This instability could enhance the afternoon convection that may
form on Wednesday. Therefore, we encourage our residents and
visitors to monitor weather conditions, as we will update them as
conditions require.

&&

.Long Term(Thursday through next Sunday)...
Issued at 148 AM AST Mon Jun 8 2026

The long term period will start relatively wet with the arrival of
an upper level trough from the northwest and a tropical wave
approaching the Caribbean from the east. Precipitable water (PWAT)
values can reach up to 1.9 inches (high-end normal values for this
time of the year) according to latest model guidance. These systems
will result in instability as 500mb temperatures cool to -7 to -9 C.
This can aid in shower and t-storm formation. Isolated to scattered
showers are forecast to move over windward sections of the islands
throughout the day, while afternoon convection (including t-storms)
should concentrate over interior and W-NW Puerto Rico. Lines of
showers can also develop from El Yunque and the local islands. This
activity can result in ponding of water over roadways and poorly
drained areas, along with urban and small stream flooding, gusty
winds and lightning. Generally drier air is forecast to filter over
the islands on Friday and Saturday, with occasional patches of
higher moisture also filtering in. However, limited flooding risk is
forecast at least on Friday. In general PWAT values should remain
below normal as available moisture is also limited to the lower
levels with drier mid-levels. Troughiness however will also persist
in the upper levels as troughs continue to linger north of the
islands, however by the weekend subsidence will dominate. In general
passing shower activity will continue to reach windward sectors at
times with diurnal heating and local effects aiding in afternoon
convection. This activity will be steered by up to breezy east to
east-southeast steering flow, as another surface high builds over
the Atlantic and tightens the local pressure gradient. More humid
patches of moisture are then forecast to reach the area by Sunday
and Monday, with PWAT values possibly reaching above normal values
and ultimately enhancing in the above mentioned diurnal pattern.
Saharan Dust will continue to filter over the local islands during
the long term period, current model guidance suggests moderate
concentrations continuing to reach the region on Thursday,
persisting, albeit gradually decreasing in concentrations,
throughout the end of the period. Current model guidance also
suggests higher concentrations approaching the islands and
eventually reaching beyond the long term period, stay tuned for more
updates. 925 mb temperatures will continue at or above normal,
prompting a possible limited to elevated heat risk each late morning
to afternoon. Heat indices can reach and exceed 100 degrees F
towards Heat Advisory Criteria at urban and lower elevations areas
of the islands, particularly to start the long term period.

&&

.AVIATION...
(18Z TAFS)
Issued at 152 PM AST Mon Jun 8 2026

Mainly VFR conditions are present across all TAF sites. VCSH and
SHRA possible across TJBQ around from 08/19Z-21Z. HZ have been
decreasing, but low to moderate concetrations will remain present
over the forecast period and could result in VIS reductions. ESE
winds around 12-18 kts with higher gusts and sea breeze variations
thru 08/22-23Z, becoming 10 kts or less overnight. Winds increasing
around 14 to 16 kts aft 09/14Z.

&&

.MARINE...
Issued at 152 PM AST Mon Jun 8 2026

The Azores high-pressure and a developing surface pressure in the
western Atlantic will produce moderate east to east-southeast
winds across regional waters, with occasional fresh winds causing
choppy conditions, especially offshore. A tropical wave is
expected to move through the Lesser Antilles on Wednesday,
reaching Puerto Rico and the U.S. Virgin Islands by Thursday. This
wave is likely to increase shower and thunderstorm activity, with
the greatest potential from Thursday afternoon to evening.
Mariners should prepare for stronger winds and higher seas near
thunderstorms.

&&

.BEACH FORECAST...
Issued at 152 PM AST Mon Jun 8 2026

There`s still potential for life-threatening rip currents along
the exposed beaches, mainly due to breezy east-southeast winds
through today. Therefore, beachgoers are urged to exercise
caution, remain aware of surf conditions, and avoid venturing too
far from shore, as life-threatening rip currents are possible
across most of the region.

From Tuesday to Wednesday, the weakening winds will lessen the
risk of rip currents; however, please exercise caution on our
local beaches, as rip currents may still occur.

Life-threatening rip currents will possibly return from Thursday
onward, especially along the east and north-facing beaches in PR
and the USVI.

&&

.FIRE WEATHER...
Issued at 152 PM AST Mon Jun 8 2026

Drier-than-normal conditions will enhance the availability of
burning fuels along the southern plains of PR and the USVI.

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...Heat Advisory until 5 PM AST this afternoon for PRZ001>003-005-
     007-008-010>013.

VI...Heat Advisory until 5 PM AST this afternoon for VIZ001-002.

AM...None.
&&

$$

DAY SHIFT...CAM/YZR
EVENING SHIFT...MNG/MRR

NWS SJU Office Area Forecast Discussion