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861
FXCA62 TJSJ 291837
AFDSJU

Area Forecast Discussion
National Weather Service San Juan PR
237 PM AST Wed Jul 29 2026

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

.KEY MESSAGES...
Updated at 235 PM AST Wed Jul 29 2026

 - Dangerous heat indices remains. Therefore, an Extreme Heat
   Warning remains in effect for the urban and coastal areas
   Puerto Rico until 5 PM AST today. A Heat Advisory remains in
   effect for the US Virgin Islands through 5 PM today. Additional
   Heat product may be needed through the remainder of the week.

 - Some showers and thunderstorms will continue to develop this
   afternoon, mainly across northwestern portions of Puerto Rico,
   producing frequent lightning, strong wind gusts, torrential
   rainfall, and localized flooding.

 - Increasing easterly winds will continue to generate choppy seas
   through the week, resulting in building seas, potentially small
   craft advisories and a higher risk of life-threatening rip
   currents along exposed beaches.

 - A drier air mass accompanied by Saharan dust will gradually
   overspread the region through at least Friday. Expect hazy
   skies, reduced air quality, and temperatures remaining above
   normal despite a decrease in overall rainfall coverage.

 - Another tropical wave may approach the region late by Sunday
   into early next week. Although forecast confidence remains low,
   it could lead to increased showers and thunderstorms.

&&

.Short Term(This evening through Friday)...
Issued at 235 PM AST Wed Jul 29 2026

Mainly fair weather conditions and hazy skies have prevailed
across the forecast area throughout the morning hours, with the
exception of a few light passing showers across the eastern half
of Puerto Rico. The primary hazard today has been the heat. As
mentioned in the previous update, the Heat Advisory for Puerto
Rico was upgraded to an Extreme Heat Warning as heat indices
exceeding warning criteria became more widespread across coastal
and urban areas due to the combination of high temperatures and
elevated humidity. Continue to take the necessary precautions,
especially if spending prolonged periods outdoors during the peak
heating hours.

A record high temperature of 94F was observed today in the San
Juan Area at the Luis Munoz Mar?n International Airport climate
station. This breaks the previous record of 93F, set in 1984 and
2013. This also marks the second consecutive day that this
official climate station has set a new daily maximum temperature
record and the eighth consecutive day with a maximum temperature
of 90F or higher.

For the remainder of the afternoon, convection driven by daytime
heating, sea breeze convergence, and local orographic effects is
expected to develop across the west-central to northwestern
portions of Puerto Rico. Although activity should remain
localized, isolated thunderstorms may produce ponding of water on
roads and in poorly drained areas.

As the Atlantic high pressure continues to strengthen, tightening
the local pressure gradient, easterly to southeasterly winds have
generally ranged between 15 and 20 mph, with occasional gusts of
25 to 30 mph. The breezier days are expected from the rest of
today and Thursday. Behind the departing tropical moisture, a
drier air mass will overspread the region after 6 PM AST this
afternoon and Thursday. The latest model guidance remains
consistent in indicating precipitable water values below 1.5
inches, or around the 25th percentile of climatological normal.
This drier air mass will be accompanied by low to moderate
concentrations of Saharan dust, which are expected to linger
through at least early Friday. Nevertheless, available low-level
moisture and daytime heating will continue to support localized
afternoon showers and isolated thunderstorms, mainly across the
northwestern quadrant of Puerto Rico, although coverage should
remain limited. On Friday, a weak wind perturbation is expected to
move across the region, resulting in a brief increase in passing
showers over the windward areas of Puerto Rico and the U.S. Virgin
Islands before the typical afternoon convection redevelops across
the interior and western portions of Puerto Rico.

For the remainder of the short-term forecast period, warm to hot
conditions will persist across coastal and urban areas. Residents
and visitors are encouraged to stay hydrated, limit outdoor
activities during the hottest part of the day, and continue
practicing heat safety measures.

&&

.Long Term(Saturday through Wednesday)...
Issued at 313 AM AST Wed Jul 29 2026

A variable weather pattern continues for the long-term forecast
period. A strong surface high-pressure system located over the
central Atlantic will maintain breezy conditions under a
southeasterly wind flow through Monday. A tropical wave and an upper-
level low are approaching the local area early next week, increasing
moisture and instability across the northeastern Caribbean region.

The latest model guidance continues to suggest seasonal precipitable
water (PWAT) values between 1.60 and 1.80 inches on Saturday.
However, from early Sunday through late Monday, PWAT values will
gradually increase as the tropical wave and upper-level low position
over the region, bringing above-normal PWAT values of 2.00 to 2.10
inches. As the upper-level low arrives, cool mid-level temperatures
(around -6 to -7 degrees Celsius at 500 mb) combined with enhanced
lifting will promote cloud growth and atmospheric instability.

During this weather scenario, frequent passing showers are expected
across portions of eastern Puerto Rico and the U.S. Virgin Islands,
followed by afternoon convective activity across central and western
Puerto Rico. Showers and thunderstorms accompanied by frequent
lightning are anticipated during this period. Due to current drought
conditions, any rainfall will be beneficial for the islands
regardless of where it falls. Elevated temperatures will persist
throughout the perioddriven by normal to above-normal temperatures
at the 925 mb levelwith daytime highs reaching the upper 80s to low
90s across coastal and urban areas.

By Wednesday, another mid-to-upper-level low will approach the
region, further increasing instability and moisture. However,
uncertainty remains regarding exact impacts. Residents and visitors
are encouraged to stay informed and monitor weather updates as the
week progresses.

&&

.AVIATION...
(18Z TAFS)
Issued at 235 PM AST Wed Jul 29 2026

Mainly VFR conditions are expected across most TAF sites during
this forecast period, except at TJBQ where VCTS/TSRA will remain
more probable, likely resulting in intermittent MVFR conditions
thru 29/21Z. The presence of low to moderate concentrations of
Saharan dust across the region will lead to slight reductions in
visibility from this afternoon into the coming days. Another
aviation concern will be the winds, with gusts near 30 kt expected
today thru 29/23Z and returning 30/13Z through 30/23Z.

&&

.MARINE...
Issued at 235 PM AST Wed Jul 29 2026

The surface high pressure over the central Atlantic will continue
to strengthen, tightening the pressure gradient and promoting
moderate to locally fresh east to east-southeast for the next few
days. These conditions will maintain periods of choppy seas across
portions of the local Atlantic and Caribbean waters, including
the local passages. This could potentially generate dangerous
conditions for small crafts. Moderate concentrations of Saharan
Dust will bring hazy skies and slightly reduce visibility
throughout the workweek. An approaching tropical wave is forecast
to reach the region late in the weekend.

&&

.BEACH FORECAST...
Issued at 235 PM AST Wed Jul 29 2026

Expect the moderate risk of rip currents to prevail across exposed
beaches of northern and eastern Puerto Rico, including Vieques
and Culebra, and the U.S. Virgin Islands. As winds continue to
strengthen, the moderate risk will spread across southern Puerto
Rico, while the western beaches remain under a low risk. Although
the risk is not high, beachgoers should continue to exercise
caution as life-threatening rip currents remain possible along the
surf zone. The moderate risk should persist throughout the
workweek, but it may downgrade along southern beaches of Puerto
Rico and St. Thomas and St. John in the U.S. Virgin Islands as
winds weaken once again during the weekend. Nevertheless,
beachgoers should be aware of life-threatening rip currents in the
vicinity of jetties, groins, reefs, and piers. Besides rip
currents, beachgoers should stay weather alert as showers and
isolated thunderstorms could still be expected in the afternoons.

&&

.FIRE WEATHER...
Issued at 235 PM AST Wed Jul 29 2026

Relative humidity values remained near or above critical
thresholds today with breezy to windy conditions. Critically dry
fuels persist across southern Puerto Rico and St. Croix. East-
southeasterly winds are forecast to remain breezy to windy through
the rest of the workweek, which could promote the spread of any
fire that develops. Additionally, a drier airmass accompanied by
Saharan dust will spread over the region later this afternoon and
tomorrow, leading to more favorable conditions for fire spread.
Residents and visitors should avoid outdoor burning and exercise
caution with activities that could generate sparks or open flames.
Fire weather partners should continue to monitor the forecast,
particularly tomorrow, Thursday.

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...Extreme Heat Warning until 5 PM AST this afternoon for
     PRZ001>005-007-008-010-011.

     Heat Advisory until 5 PM AST this afternoon for PRZ012-013.

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

AM...None.
&&

$$

SHORT TERM/AVIATION/FIRE...YZR
LONG TERM...GRS
MARINE/BEACH...MMC

NWS SJU Office Area Forecast Discussion