textproduct: San Juan

KEY MESSAGES

Issued at 245 PM AST Fri Aug 14 2026

- A tropical wave known as Invest 92L will move across the Caribbean Sea, increasing moisture across the area from late Saturday into Sunday morning. Therefore, residents can expect an increase in fast-moving showers.

- The U.S. Virgin Islands might experience passing showers from Saturday afternoon into Sunday due to Invest 92L.

- Saharan dust particles will remain across the region for the rest of today into Saturday morning.

- Hazardous marine and coastal conditions are forecast through the weekend. For more detailed information, please refer to the Marine and Beach Forecast sections.

Short Term(This evening through Sunday)

Issued at 245 PM AST Fri Aug 14 2026

The day started with fair weather conditions as a drier airmass prevailed over the region. The TJSJ 14/12Z upper-air sounding indicated precipitable water values around 1.35 inches, which is considered below normal. Dry air in the mid-levels, accompanied by a persistent trade-wind cap, have been preventing deep vertical cloud development across most of the area. Hazy skies have persisted as moderate to locally high concentrations of Saharan dust remain over the region through at least Saturday (tomorrow) afternoon, as another pulse arrives during the overnight and Saturday morning based on the latest guidance models. Temperatures have been reaching the low 90s across coastal and urban areas, while heat indices have reached Heat Advisory criteria, with the highest observed values around 110-111F. Winds have been predominantly from the east-southeast at 15 to 25 mph, with some sea-breeze variations influencing the local wind direction. Gusts have occasionally exceeded 28 mph, particularly across exposed and coastal areas. As a result, a Heat Advisory remains in effect until 6 PM AST this afternoon, and a Fire Danger Statement until 4 PM AST.

For the remainder of the afternoon and through Saturday, hazy skies, breezy conditions, and generally limited rainfall are expected to persist. Moisture will increase Saturday night into Sunday as Invest 92L and its associated moisture field approach the eastern Caribbean. Current guidance generally suggests AL92 will move as a tropical wave, with the bulk of the deeper moisture remaining well south of the local islands over the Caribbean waters. Nevertheless, PWAT values are expected to increase to around 1.7 to 1.9 inches on Sunday, supporting a gradual increase in overnight and morning passing showers, followed by locally driven afternoon convection across Puerto Rico. Winds will remain breezy to windy, and any shower will be fast-moving, reducing the chance to observe significant accumulations. The strongest convection on Sunday may bring locally heavy rainfall, isolated thunderstorms, and gusty winds, but a widespread rainfall event is not expected. Overall, through Saturday, heat, fire weather, and breezy to locally windy conditions will remain the primary concerns, while Sunday will bring a better chance for showers and thunderstorms as peripheral moisture associated with AL92 briefly reaches the region, but no widespread rain event in anticipated.

Long Term(Monday through Friday)

Issued at 230 AM AST Fri Aug 14 2026

Variable conditions are expected through the period, with generally east to east-southeast winds and increasing uncertainty late next week. On Monday, moisture trailing AL92 may support passing windward showers and afternoon thunderstorms across western Puerto Rico. Another increase in Saharan dust is also possible. A trade-wind perturbation may pass late Monday into Tuesday, but latest guidance keeps most of its activity north of the islands. Ponding of water and localized minor flooding remain possible with heavier afternoon showers.

A more seasonal pattern is expected Tuesday through Thursday as PWAT gradually increases to 1.5 to 1.7 inches. An upper-level low will also cool 500 mb temperatures to around -6 to -7 degrees C, increasing instability. Nighttime and morning windward showers will be followed by afternoon showers and isolated thunderstorms across interior and western Puerto Rico, particularly Tuesday and Wednesday. The flood threat should remain limited, mainly involving ponding of water, although localized urban and small-stream flooding cannot be ruled out.

Forecast uncertainty increases Thursday into Friday as the National Hurricane Center monitors AL94 southwest of the Cabo Verde Islands. Global guidance generally brings the system toward the northeastern Caribbean late next week, but differences remain in timing and intensity, including whether development occurs before the system encounters a less favorable environment. Continue to monitor the latest NHC forecasts.

AVIATION

(18Z TAFS) Issued at 245 PM AST Fri Aug 14 2026

Mainly VFR conds across TAF sites. Moderate to locally high concentrations of Saharan dust are resulting in VIS reductions at least thru Saturday afternoon. Another aviation concern are the breezy to windy conditions, winds slightly reducing overnight but overall, but aft 15/12-14Z will become gusty up to 30 to 32 kts across all TAF sites. Recent PIREPs indicate LLWS at TIST, and this conditions will remain possible throughout the forecast period.

MARINE

Issued at 245 PM AST Fri Aug 14 2026

A surface high pressure over the central Atlantic will maintain a tight pressure gradient across the northeastern Caribbean, promoting fresh to locally strong easterly winds and choppy to hazardous marine conditions through the weekend. Seas will generally build to around 7 feet, with occasional seas of 8 to 9 feet across the offshore waters and local passages. Therefore, Small Craft Advisories remain in effect through at least Sunday. On Saturday into Sunday, showers and thunderstorms are expected to increase as a tropical wave associated with Invest 92L approaches and passes mainly south of the region. The Caribbean waters and southern portions of the local passages are expected to experience the greatest increase in shower and thunderstorm activity, with locally stronger and gusty winds possible, resulting in hazardous seas conditions.

BEACH FORECAST

Issued at 245 PM AST Fri Aug 14 2026

A broad surface high pressure over the Central Atlantic and a tropical wave will hold breezy conditions along the CWA. This will hold choppy to hazardous surf conditions across the local beaches through the weekend. As a result, a high risk of life-threatening rip currents will persist along most beaches of Puerto Rico, Vieques, Culebra, and the U.S. Virgin Islands. Rip Current Statements remain in effect through late Saturday night. Beaches along western Puerto Rico are expected to remain under a moderate risk for the upcoming days. Beachgoers are urged to exercise caution, swim near lifeguards, and follow beach patrol flags and posted signs. Additionally, breezy to windy conditions along exposed coastal areas may blow around unsecured objects.

FIRE WEATHER

Issued at 245 PM AST Fri Aug 14 2026

Surface observations have been showing winds and minimum relative humidity values reaching the critical fire weather thresholds today. Combined with dry fuels and strong easterly winds is favoring rapid fire spread, particularly across the southern coastal plain and adjacent slopes of Puerto Rico. A Fire Danger Statement remains in effect until 4 PM AST. Dry and breezy conditions will continue through much of Saturday before increasing moisture Saturday night into Sunday raises relative humidity and reduces fire weather concerns.

SJU WATCHES/WARNINGS/ADVISORIES

PR...High Rip Current Risk through late Sunday night for PRZ001>003- 005-007-008-011>013.

Heat Advisory until 6 PM AST this evening for PRZ001>005-007-008- 010>013.

VI...High Rip Current Risk through late Sunday night for VIZ001-002.

Heat Advisory until 6 PM AST this evening for VIZ001-002.

AM...Small Craft Advisory until 5 PM AST Sunday for AMZ711-723-733- 741.

Small Craft Advisory until 1 PM AST Saturday for AMZ712-716-726- 735.