384
FXCA62 TJSJ 250716
AFDSJU
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
316 AM AST TUE AUG 25 2026
...NEW SHORT TERM, LONG TERM, AVIATION, MARINE, BEACH FORECAST, FIRE WEATHER...
KEY MESSAGES
ISSUED AT 309 AM AST TUE AUG 25 2026
* DANGEROUS HEAT: ELEVATED TO LOCALLY SIGNIFICANT HEAT RISKS FOR THE
US VIRGIN ISLANDS AND PUERTO RICO WILL PERSIST THROUGH THE
PERIOD, WITH THE POTENTIAL FOR EXTREME HEAT, PARTICULARLY
WEDNESDAY AND AGAIN EARLY NEXT WEEK.
* TUESDAY FLOODING: A WEAK TROPICAL WAVE WILL INCREASE SHOWERS
AND THUNDERSTORMS TODAY, RAISING FLOODING RISK TO LIMITED TO
ELEVATED LEVELS, MAINLY ACROSS INTERIOR, WESTERN, AND NORTHERN
PUERTO RICO.
* SAHARAN DUST: DRIER AIR AND MODERATE SAHARAN DUST
CONCENTRATIONS WILL PROMOTE HAZY SKIES ACROSS THE US VIRGIN
ISLANDS AND PUERTO RICO TUESDAY NIGHT THROUGH WEDNESDAY, ALONG
WITH REDUCED RAINFALL COVERAGE.
* WET WEEKEND: A TROPICAL WAVE WILL BRING DEEPER MOISTURE FRIDAY
NIGHT INTO THE WEEKEND, WITH SATURDAY HAVING THE GREATEST
POTENTIAL FOR INCREASED RAINFALL AND FLOODING. FORECAST
UNCERTAINTY INCREASES EARLY NEXT WEEK DUE TO THE FUTURE
EVOLUTION OF AL96.
* INCREASING RIP CURRENT RISK: THE POTENTIAL FOR LIFE-
THREATENING RIP CURRENTS WILL INCREASE TO MODERATE FROM
WEDNESDAY NIGHT ONWARD, ESPECIALLY ALONG MOST EXPOSED BEACHES OF
PUERTO RICO AND THE US VIRGIN ISLANDS.
SHORT TERM(TODAY THROUGH THURSDAY)
ISSUED AT 309 AM AST TUE AUG 25 2026
ANOTHER WARMER-THAN-NORMAL NIGHT PREVAILED OVERNIGHT, WITH LOWS
IN THE UPPER 70S OR LOW 80S, OR EVEN THE MID 80S ALONG COASTAL
SECTIONS, AND IN THE LOW 70S IN MOUNTAINS AND VALLEYS. SKIES WERE
MOSTLY CLEAR, WITH SOME LOW-LEVEL CLOUDS PUSHED BY THE WINDS, BUT
INFRARED SATELLITE IMAGERY ALSO SHOWED A DENSE TO THIN LAYER OF
MID- TO UPPER-LEVEL CLOUDS SPREADING FROM THE WEST. DOPPLER RADAR
DETECTED SHOWERS MAINLY OVER THE LOCAL WATERS ASSOCIATED WITH THE
APPROACHING WEAK WAVE, AND SOME MOVED INLAND ACROSS THE WINDWARD
LOCATIONS. MOST OF THE ISLANDS OBSERVED LIGHT TO CALM WINDS UNDER
LAND BREEZE INFLUENCE; HOWEVER, SOME STATIONS NEAR CULEBRA, ST
THOMAS, AND CAJA DE MUERTO REPORTED WINDS BETWEEN 10 AND 20 MPH.
A WEAK TROPICAL WAVE WILL MOVE ACROSS THE US VIRGIN ISLANDS AND
PUERTO RICO TODAY, INCREASING MOISTURE AND SUPPORTING AN ELEVATED
TO LOCALLY SIGNIFICANT HEAT RISK. A HEAT ADVISORY IS IN EFFECT
FROM 10 AM TO 5 PM AST. INCREASING MOISTURE AND LOW-LEVEL
CONVERGENCE WILL ALSO FAVOR SHOWERS AND THUNDERSTORMS ACROSS THE
USVI AND EASTERN PUERTO RICO THROUGH EARLY AFTERNOON, SHIFTING
TOWARD INTERIOR, WESTERN, AND NORTHERN PUERTO RICO LATER TODAY. A
LIMITED TO ELEVATED FLOODING RISK IS POSSIBLE WITH THE STRONGEST
AFTERNOON THUNDERSTORMS. MEANWHILE, AREAS RECEIVING LESS RAINFALL,
PARTICULARLY SOUTHERN PUERTO RICO AND PORTIONS OF THE USVI, WILL
EXPERIENCE THE HIGHEST HEAT INDICES.
DRIER AIR WITH MODERATE SAHARAN DUST CONCENTRATIONS WILL FOLLOW
THE WAVE TONIGHT INTO WEDNESDAY, RESULTING IN HAZY SKIES, REDUCED
RAINFALL COVERAGE, AND ANOTHER WARMER-THAN-NORMAL NIGHT. HEAT WILL
REMAIN THE PRIMARY HAZARD WEDNESDAY, WITH ABOVE-NORMAL
TEMPERATURES SUPPORTING A SIGNIFICANT TO POTENTIALLY EXTREME HEAT
RISK. AN EXTREME HEAT WARNING MAY BECOME NECESSARY DEPENDING ON
CLOUD AND RAINFALL COVERAGE.
ANOTHER MOISTURE SURGE WILL ARRIVE LATE WEDNESDAY NIGHT INTO
THURSDAY, GRADUALLY REDUCING SAHARAN DUST AND INCREASING PASSING
SHOWERS. AFTERNOON CONVECTION WILL REMAIN POSSIBLE ACROSS INTERIOR
AND WESTERN PUERTO RICO. WIDESPREAD FLOODING IS NOT ANTICIPATED
WEDNESDAY OR THURSDAY, BUT A LIMITED FLOODING RISK WILL PERSIST
WITH LOCALLY HEAVY AFTERNOON SHOWERS.
LONG TERM(FRIDAY THROUGH TUESDAY)
ISSUED AT 309 AM AST TUE AUG 25 2026
PATCHES OF MOISTURE WITH SEASONAL PRECIPITABLE WATER (PWAT) VALUES
WILL MOVE ACROSS THE ISLANDS ON FRIDAY UNDER A GENERALLY EASTERLY
STEERING FLOW TO START THE LONG TERM PERIOD, BRINGING IN SHOWERS
OVER WINDWARD SECTORS TO START THE MORNING HOURS. DIURNAL HEATING,
SEA BREEZE CONVERGENCE AND LOCAL EFFECTS WILL ALSO RESULT IN
AFTERNOON SHOWERS AND T-STORMS OVER MAINLY WESTERN PUERTO RICO.
AVAILABLE MOISTURE HOWEVER WILL BE MOSTLY LIMITED TO THE LOWER
LEVELS. AN ELEVATED HEAT RISK IS ALSO POSSIBLE OVER URBAN AND
COASTAL SECTORS.
A TROPICAL WAVE, AND ITS ASSOCIATED MOISTURE FIELD, WILL THEN
APPROACH THE ISLANDS FRIDAY NIGHT AND PUSH PWAT VALUES TO ABOVE
NORMAL, ABOVE 2 INCHES, THROUGH AT LEAST THE OVERNIGHT HOURS
SATURDAY INTO SUNDAY. AVAILABLE MOISTURE CAN ALSO REACH DEEPER IN
THE ATMOSPHERE, FURTHER PROMPTING A FLOODING RISK. STEERING FLOW
WILL BE GENERALLY ESE AND CAN RESULT IN SHOWERS AND POSSIBLE T-
STORMS MOVING OVER THE ISLANDS DURING THE OVERNIGHT AND MORNING
HOURS, WHILE AFTERNOON SHOWERS AND T-STORMS ARE FORECAST TO DEVELOP
OVER INTERIOR TO W-NW PR AS WELL AS DOWNWIND OF THE LOCAL ISLANDS
AND EL YUNQUE. THIS PERIOD IS FORECAST TO BE THE MOST HUMID AND THE
MOST LIKELY TO FEATURE INCREASED RAIN CHANCES.
DRIER AIR IS THEN FORECAST TO MOVE OVER THE AREA ON SUNDAY,
RESULTING IN BELOW NORMAL PWAT VALUES AND, ACCORDING TO THE LATEST
GUIDANCE, MORE MODERATE SAHARAN DUST CONCENTRATIONS MOVING OVER THE
AREA AS AVAILABLE MOISTURE IS ONCE AGAIN CONFINED TO THE LOWER
LEVELS. AFTERNOON CONVECTION IS STILL FORECAST OVER W TO NW UNDER
ESE STEERING FLOW. UNCERTAINTY INCREASES TO START THE NEXT WORKWEEK
DUE TO THE TROPICAL WAVE AL96 CURRENTLY OVER THE EASTERN TROPICAL
ATLANTIC (PLEASE SEE THE LATEST TROPICAL WEATHER OUTLOOK FOR THE
MOST UP TO DATE INFORMATION REGARDING THIS WAVE). THE CURRENT
FORECAST IS BASED ON GENERALLY EASTERLY STEERING FLOW VEERING TO
BECOME MORE SOUTH-SOUTHEASTERLY AND STEERING PATCHES OF MOISTURE AND
DRIER AIR OVER THE ISLANDS, WITH SHOWERS MOVING OVER WINDWARD
SECTORS AND AFTERNOON CONVECTION DEVELOPS. GIVEN FORECAST
UNCERTAINTIES, RESIDENTS AND LOCAL INTERESTS ARE ADVISED TO TRACK
UPCOMING UPDATES AS AL96 MOVES OVER THE ATLANTIC. SEASONAL TO ABOVE
SEASONAL 925 MB TEMPERATURES WILL PERSIST DURING THE PERIOD AND
RESULT IN ELEVATED TO POSSIBLY SIGNIFICANT HEAT RISKS EACH DAY, WITH
THE HIGHEST CHANCES OF A MORE LIMITED HEAT RISK BEING ON SATURDAY.
AVIATION
(06Z TAFS)
ISSUED AT 309 AM AST TUE AUG 25 2026
EXPECT MAINLY VFR CONDS. A WEAK TROPICAL WAVE WILL INCREASE
SHRA/TSRA ACTIVITY TODAY, INITIALLY AFFECTING THE USVI AND E-PR
TERMINALS DURING THE MORNING, THEN SHIFTING TOWARD INTERIOR/W-PR
AFT 25/15Z. BRIEF MVFR/IFR CONDS AND MNT OBSC ARE POSSIBLE WITH
THE STRONGEST ACTIVITY, PARTICULARLY NEAR TJBQ. WINDS GENERALLY
FROM THE E AT 10-15 KT, WITH SEA-BREEZE VARIATIONS AND HIGHER
GUSTS NEAR SHRA/TSRA. SAHARAN DUST WILL INCREASE TONIGHT INTO
WEDNESDAY, PRODUCING HAZY SKIES BUT GENERALLY VFR CONDS.
MARINE
ISSUED AT 309 AM AST TUE AUG 25 2026
A SURFACE HIGH PRESSURE OVER THE WESTERN ATLANTIC IS EXPECTED TO
BUILD AND EXTEND INTO THE CENTRAL ATLANTIC. THIS WILL PROMOTE
MODERATE EAST-SOUTHEASTERLY WINDS ACROSS THE AREA, BECOMING
MODERATE TO LOCALLY FRESH OCCASIONALLY. A TROPICAL WAVE IS
FORECAST TO APPROACH THE NORTHEASTERN CARIBBEAN TODAY, BRINGING
ENHANCED SHOWER AND THUNDERSTORM ACTIVITY ACROSS THE LOCAL WATERS
AND PASSAGES. SAHARAN DUST CONCENTRATIONS WILL GRADUALLY INCREASE
LATER TONIGHT, PEAKING ON WEDNESDAY, BRINGING HAZY SKIES AND
SLIGHTLY REDUCED VISIBILITY. A WEAK LONG-PERIOD SWELL SHOULD
ARRIVE AND SPREAD ACROSS THE REGIONAL WATERS BY THURSDAY.
BEACH FORECAST
ISSUED AT 309 AM AST TUE AUG 25 2026
A LOW RISK OF RIP CURRENTS WILL CONTINUE THROUGH WEDNESDAY EVENING
ACROSS THE LOCAL ISLANDS. NONETHELESS, BEACHGOERS MUST EXERCISE
CAUTION, AS LIFE-THREATENING RIP CURRENTS CAN OFTEN OCCUR IN THE
VICINITY OF JETTIES, REEFS, GROINS, AND PIERS.
BY WEDNESDAY EVENING, A GRADUAL INCREASE IN WINDS AND SEAS WILL
LIKELY UPGRADE THE RISK TO MODERATE, PARTICULARLY ACROSS THE
NORTHERN AND EASTERN-EXPOSED BEACHES OF THE ISLANDS, INCREASING
THE LIKELIHOOD OF RIP CURRENTS ALONG THE SURF ZONE. THE MODERATE
RISK SHOULD CONTINUE THROUGHOUT THE END OF THE WEEK.
AN APPROACHING TROPICAL WAVE WILL INCREASE THE FREQUENCY OF
SHOWERS AND ISOLATED THUNDERSTORMS THIS AFTERNOON ACROSS THE
REGIONAL WATERS. BEACHGOERS SHOULD REMAIN WEATHER ALERT, AS
ISOLATED THUNDERSTORMS COULD PRODUCE GUSTY WINDS AND LIGHTNING.
FIRE WEATHER
ISSUED AT 309 AM AST TUE AUG 25 2026
A MARGINAL FIRE WEATHER RISK IS EXPECTED TODAY, MAINLY DUE TO THE
PRESENCE OF DRY FUELS. WINDS WILL REMAIN BELOW NORMAL, LIMITING
THE POTENTIAL FOR RAPID FIRE SPREAD. RELATIVE HUMIDITY VALUES MAY
BRIEFLY DROP DURING PEAK HEATING; HOWEVER, INCREASED TROPICAL
MOISTURE ASSOCIATED WITH THE PASSING TROPICAL WAVE SHOULD
GENERALLY KEEP RH ABOVE CRITICAL LEVELS. THEREFORE, DESPITE THE
DRY FUELS, THE COMBINATION OF LIGHTER WINDS AND HIGHER MOISTURE
SHOULD LIMIT THE OVERALL FIRE WEATHER THREAT.
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....MRR
MARINE/BEACH FORECAST...GRS
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