textproduct: San Juan

KEY MESSAGES

Issued at 244 PM AST Sat Aug 15 2026

- A tropical wave moving across the Caribbean Sea will gradually increase moisture from the rest of today into Sunday morning. Therefore, residents can expect an increase of fast-moving showers. Drier air will filter behind bringing low to moderate concentrations of Saharan dust.

- Breezy to windy conditions will continue through at least late Sunday, secure loose objects as they could blow around.

- A Heat Advisory is in effect through 5 PM AST for urban and coastal areas of Puerto Rico and the U.S. Virgin Islands.

- Hazardous marine and coastal conditions are ongoing and will continue through at least late Sunday. Small Craft Advisories and Rip Current Statement are in effect.

- A Red Flag Warning was issued for the coastal plains and hills of southern Puerto Rico and Vieques, while a Fire Danger Statement remains in effect for the rest of the areas.

Short Term(This evening through Monday)

Issued at 244 PM AST Sat Aug 15 2026

The day will remain windy with mostly cloudy skies. Around 9 AM AST, satellite imagery showed cloudiness associated with the outer bands of the tropical wave moving south of the area, reaching the islands. According to unofficial weather stations across the islands, wind gusts of up to 41 mph were reported in Culebra and St. John, while gusts generally ranged from 30 to 35 mph across the main islands. Across Puerto Rico, sustained winds generally ranged from 20 to 26 mph. The Luis Munoz Marin International Airport station reported a maximum wind gust of 35 mph, with sustained winds between 22 and 26 mph. As of 11 AM AST, Doppler radar indicated quick-moving showers across northern and central Puerto Rico, affecting areas from Bayamon westward toward Utuado. These showers were generally brief due to the fast steering flow. Maximum daytime temperatures were in the low 90s across northern and southern coastal areas and in the 80s across the rest of the island. Maximum heat indices ranged from 108 to 112 degrees across portions of north-central Puerto Rico and the southern coastal areas.

For the rest of the day, variable weather conditions will prevail as the tropical wave known as Invest 92L continues to move westward across the Caribbean Sea. Moisture associated with the system will continue to move across the islands; however, the bulk of the shower and thunderstorm activity will remain south of the CWA. According to high-resolution model guidance, an increase in rainfall activity is forecast across eastern sections from late this evening into the early Sunday morning hours. Rainfall accumulations are expected to remain limited, generally between 1 and 1.5 inches, due to the fast- moving nature of the showers. On Sunday, variable weather conditions will continue; however, the bulk of the moisture is forecast to quickly move out of the region by Sunday afternoon. Therefore, the islands can expect passing showers over the local waters and eastern sections during the morning, followed by afternoon showers across western Puerto Rico. Thereafter, the influence of a surface high pressure will maintain easterly winds across the islands through Monday. Under this pattern, a drier air mass with lower precipitable water values will move into the region, promoting a more stable weather pattern. Hazy skies will also be possible on Monday as Saharan dust particles remain across the area, as suggested by the NASA Goddard Earth Observing System Model, Version 5 (GEOS-5).

The heat threat is expected to persist throughout the period across urban and coastal areas due to warm temperatures and elevated heat indices. These conditions could increase the risk of heat exhaustion, particularly among vulnerable populations and individuals working or participating in outdoor activities during the peak heating hours of the day. Residents and visitors are encouraged to stay hydrated, limit prolonged exposure to direct sunlight, and take frequent breaks in shaded or air-conditioned areas.

Long Term(Tuesday through Saturday)

Issued at 249 AM AST Sat Aug 15 2026

A relatively dry and stable weather pattern is expected Tuesday, followed by increasing moisture and instability Wednesday into Thursday as Invest 94L (AL94) approaches the northeastern Caribbean. On Tuesday, PWAT values should remain around 1.3 to 1.5 inches, with relatively dry mid-levels limiting shower and thunderstorm coverage. Moisture will gradually increase Wednesday, with the most significant surge expected Wednesday night into Thursday, when PWAT could rise to around 2 inches or greater. Increasing low- to mid- level moisture, cooler 500 mb temperatures, and steeper mid-level lapse rates should favor increasing showers and thunderstorms, with locally heavy rainfall and urban and small-stream flooding possible.

Considerable uncertainty remains Thursday into Saturday regarding the evolution, track, timing, and moisture distribution associated with AL94. Regardless of development, the disturbance could bring a substantial tropical moisture envelope across or near the local islands. Small changes in its track or evolution could significantly influence rainfall coverage and amounts. Although moisture may fluctuate Friday into Saturday, cooler temperatures aloft and favorable mid-level lapse rates should maintain an unstable environment, supporting periods of showers and thunderstorms where deeper moisture persists. Therefore, the flooding threat will depend largely on the duration and location of the deepest moisture.

The expected rainfall could provide beneficial moisture to areas experiencing dry conditions; however, significant drought relief is not anticipated, as rainfall amounts and coverage will likely vary considerably. Heat will also remain a concern, particularly Tuesday and during periods of sufficient sunshine later in the week. Increasing humidity may maintain elevated heat indices, while greater cloud and shower coverage Thursday onward could provide some relief. Continue to monitor the latest forecasts and updates regarding the evolution of AL94..LONG TERM...

AVIATION

(18Z TAFS) Issued at 244 PM AST Sat Aug 15 2026

Breezy to windy conditions will prevail, with easterly winds between 20 and 28 knots and gusts up to 35 knots. Quick-moving SHRA are possible across the area as Invest 92L moves westward across the Caribbean Sea. Windy conditions will persist at the TAF sites overnight. SHRA with VCTS are expected at TJPS and TIST after 16/03Z as TSRA associated with the tropical wave moves near the terminals.

MARINE

Issued at 244 PM AST Sat Aug 15 2026

A tight pressure gradient will maintain fresh to locally strong easterly winds and choppy to rough seas of 5 to 7 feet, with occasional seas reaching 8 to 9 feet across the offshore waters and local passages. Small Craft Advisories remain in effect through at least late Sunday night due to this hazardous conditions. Showers and thunderstorms are expected to become more frequent from this afternoon into Sunday morning as the tropical wave moves south of the region, bringing increased shower and thunderstorm activity, particularly across the Caribbean waters and local passages.

BEACH FORECAST

Issued at 244 PM AST Sat Aug 15 2026

Tonight and Sunday, there is a high risk of rip currents across most beaches of Puerto Rico, Vieques, Culebra, and the U.S. Virgin Islands due to breezy to windy conditions producing breaking waves 6 to 7 feet. The Rip Current Statement remains in effect through at least late Sunday night. Beachgoers are urged to stay out of the water and heed the advice of lifeguards, beach patrol flags, and posted signs.

By Monday, the risk is forecast to return to moderate levels across most beaches, but life-threatening rip currents will remain possible. Tuesday into midweek, winds are expected to subside, further decreasing the risk. However, remember that even when the risk is low, life-threatening rip currents can occur near groins, jetties, reefs, and piers.

FIRE WEATHER

Issued at 244 PM AST Sat Aug 15 2026

Elevated fire danger continues today as minimum relative humidities remain around mid 40s to low 50s, particularly across the coastal plains and hills of southern Puerto Rico and Vieques. That combined with breezy to windy conditions are elevating the risk of fire spread. A Fire Danger Statement remains in effect across portions of Puerto Rico, Culebra, and the U.S. Virgin Islands until 5 PM AST this afternoon, while a Red Flag Warning was issued for the coastal plains and hills of southern Puerto Rico and Vieques.

The northern periphery of an approaching tropical wave should continue to approach, slightly increasing the moisture content across the area. Nonetheless, the dry conditions will persist until then.

SJU WATCHES/WARNINGS/ADVISORIES

PR...Heat Advisory until 5 PM AST this afternoon for PRZ001>005-007- 008-010>013.

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

Red Flag Warning until 5 PM AST this afternoon for PRZ014-015- 025-027.

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

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

AM...Small Craft Advisory until midnight AST Sunday night for AMZ711- 723-733-741.

Small Craft Advisory until noon AST Sunday for AMZ712-716-726- 735.