800
FXCA62 TJSJ 100601
AFDSJU

Area Forecast Discussion
National Weather Service San Juan PR
201 AM AST Wed Jun 10 2026

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

.KEY MESSAGES...
Issued at 132 AM AST Wed Jun 10 2026

* Cloudiness associated to an approaching trough and a weak
  tropical wave will limit the widespread potential for
  experiencing extended period of heat. Therefore, a heat
  Advisory was not issued for today.

* A wetter and more unstable weather pattern is expected on late
  today and especially Thursday as a tropical wave interacts with
  an approaching upper-level trough, increasing the coverage of
  showers and thunderstorms across the region, and posing the
  greatest risk of flooding for Thursday.

* Traces of Saharan dust will persist through the forecast period,
  producing somewhat hazy skies and reduced air quality,
  especially trailing the wave into early Saturday.

* The potential for life-threatening rip currents will turn
  moderate from Thursday onward, first across St Croix, then
  spreading to the rest of the east and north-facing beaches in
  the USVI and PR.

&&

.Short Term(Today through Friday)...
Issued at 132 AM AST Wed Jun 10 2026

Overnight, calm weather conditions prevailed across Puerto Rico and
the U.S. Virgin Islands. Mostly clear skies over urban and
coastal areas allowed temperatures to drop into the 70s, while
partly cloudy skies across the interior and higher elevations kept
temperatures in the 60s. Winds remained light and variable
through the night.

Today will remain warm, although increasing cloudiness from an approaching
trough and weak tropical wave should limit the extent of
widespread heat indices above 100F. Still, isolated north-central
and western areas of Puerto Rico could briefly reach Heat
Advisory criteria this afternoon. Residents and visitors,
especially heat-sensitive individuals, should continue following
heat safety recommendations. Lingering Saharan dust may also
affect air quality, and people with respiratory conditions are
encouraged to follow health guidance. That being said, moisture
will gradually increase as the trough and tropical wave approach
the region. This will raise the potential for showers and
thunderstorms this afternoon, mainly across the interior to
western Puerto Rico, with additional activity possible downwind of
the U.S. Virgin Islands, El Yunque, and the San Juan metropolitan
area. Periods of heavy rain could lead to ponding of water on
roads, localized urban flooding, and minor flooding in poorly
drained areas.

Thursday is expected to be the wettest and most unstable day of
the short-term forecast period. Model guidance continues to
indicate precipitable water and mid-level relative humidity values
rising into the 75th percentile or above climatological normals
for this time of year, particularly from late Wednesday into
Thursday. In addition, 500 mb temperatures near -8 degrees Celsius
will support enhanced instability aloft. This combination of
abundant moisture and favorable atmospheric conditions is expected
to promote more widespread shower and thunderstorm development.
As a result, the risk of urban and small stream flooding will
remain elevated, particularly in vulnerable and poorly drained
areas.

Conditions are expected to improve gradually by Friday as moisture
decreases and atmospheric conditions gradually stabilizes, leading
to quieter and more typical weather conditions heading into the
weekend.

&&

.Long Term(Saturday through Wednesday)...
Issued at 132 AM AST Wed Jun 10 2026

In general, drier air with embedded patches of moisture will filter
into the region steered by up to breezy E to ESE flow (backing to
become more easterly late in the period). This will steer showers
over windward sectors and, with diurnal heating and local effects,
help develop shallow afternoon convection over western/northwestern
Puerto Rico. Additionally, lines of showers can also develop
downwind of the local islands and El Yunque. Ponding of water over
roadways and poorly drained areas continues to be possible.
Discrepancies continue between the GFS and ECMWF model guidance to
start the workweek, with the GFS suggesting an upper-level trough
lingering near the region and above normal PWAT values and the ECMWF
suggesting more mid-level ridging and generally drier air. The GFS
seems to lean more towards a ridging pattern than yesterday; a more
seasonal pattern was added to start the next week. 925 mb
temperatures are forecast to continue at or above normal, prompting
a limited to possible elevated heat risk each late morning to late
afternoon. Heat indices can reach and exceed 100 degrees Fahrenheit
at urban and lower elevations areas of the islands. Saharan Dust
will continue to filter over the local islands during the long term
period.  Current model guidance also suggests higher concentrations
approaching the islands after the long term period.

&&

.AVIATION...
(06Z TAFS)
Issued at 132 AM AST Wed Jun 10 2026

VFR conditions across all TAF sites. Expect the SE winds around
8-15 kt with higher gusts and sea breeze after 10/13Z. VCSH and
VCTS possible across western Puerto Rico, affecting TJBQ between
10/18Z and 10/23Z.

&&

.MARINE...
Issued at 132 AM AST Wed Jun 10 2026

The Azores high pressure and a surface high building in the western
Atlantic will promote light to moderate east to east-southeast winds
across regional waters, becoming moderate to locally fresh by
Friday. Strengthening winds will result in choppy seas, particularly
across offshore waters, that may create locally hazardous conditions
for small craft. A tropical wave approaching the Caribbean Basin
will likely increase shower and thunderstorm activity on Thursday,
particularly during the afternoon and evening. Mariners should
exercise caution as stronger winds and higher seas can be expected
near thunderstorms.

&&

.BEACH FORECAST...
Issued at 132 AM AST Wed Jun 10 2026

No changes were introduced to the beach forecast. The low risk of
rip currents should continue today as winds remain weak, resulting
in breaking waves between 1 and 3 feet across most beaches of the
islands. Although the risk is low, beachgoers should be aware of
isolated, stronger rip currents that may occur, particularly near
groins, jetties, reefs, and piers. As the local pressure gradient
gradually increases, winds should strengthen Thursday onward,
increasing the risk of rip currents to moderate. The risk should
begin over the northern and eastern beaches of Puerto Rico,
spreading across most beaches of the islands by the weekend into
early next week. Under a moderate risk, life-threatening rip
currents are possible along the surf zone, beachgoers must exercise
caution.

Besides rip currents, beachgoers should keep in mind the possibility
of showers and isolated thunderstorms moving over coastal areas each
afternoon through Friday, with a higher chance over western and
northern Puerto Rico. Beachgoers can expect gusty winds and
lightning near thunderstorms, and they must seek shelter whenever
they hear thunder.

&&

.FIRE WEATHER...
Issued at 132 AM AST Wed Jun 10 2026

RH values will range around 40 to 50 percent but will increase
gradually by late today through Thursday. Winds will remain
relatively low or below 15 mph meaning that there are limiting
factors for maintaining an elevated fire threat for today.
Therefore, expect a LOW fire weather risk across the southern
sections of the islands, as brief conditions will be present.

&&

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

$$

SHORT TERM/AVIATION/FIRE WEATHER...MMC
LONG TERM...MRR
MARINE/BEACH FORECAST...MNG

NWS SJU Office Area Forecast Discussion