textproduct: San Juan

KEY MESSAGES

Updated at 225 PM AST Wed Apr 15 2026

* Afternoon showers and thunderstorms will continue through the afternoon hours across northwestern Puerto Rico.

* Increasing instability from tomorrow and Friday, associated with an amplifying upper-level trough and enhanced moisture availability, will promote an active weather pattern, particularly each afternoon across northwest Puerto Rico.

* Southeasterly low-level winds will promote slightly above-normal temperatures across low-elevation and urban areas.

* A moderate risk of rip currents will persist along the north- exposed beaches of the islands over the next several days.

Short Term(This evening through Friday)

Issued at 225 PM AST Wed Apr 15 2026

During the morning hours, a mix of clear to partly cloudy skies prevailed across the region, with only a few light showers and minimal accumulations over Vieques, Culebra, and the U.S. Virgin Islands. Winds were mainly from the east to southeast at around 10 to 15 mph, with occasional higher gusts. Daytime maximum temperatures have ranged from the low to mid-80s across low- elevation, urban, and coastal areas, and from the 70s to the low 80s in the mountainous regions. Across the USVI, temperatures have fluctuated in the upper 80s. Around noon, strong convective shower activity began developing from the northern slopes into the northern municipalities, prompting Flood Advisories and Special Weather Statements due to a strong thunderstorm producing heavy rain, wind gusts, and possible small hail.

For the rest of the afternoon, scattered to numerous showers and thunderstorms are expected to continue moving across the north- central into northwestern municipalities. This will result in a continued elevated flood risk, including flooding in urban areas, along roads and in small streams, as well as ponding of water in poorly drained areas. Gusty winds and the potential for landslides in steep terrain are also concerns. As the sun sets, activity should diminish, leading to calmer conditions early tonight.

During the overnight hours into Thursday morning, the latest high-resolution models suggest the development of isolated to scattered showers across the waters, the USVI, Vieques, Culebra, and eastern Puerto Rico. Conditions will become slightly more favorable for instability as the cut-off low continues to drift northeast and the upper-level trough amplifies just west of the region, maintaining the divergent side of the system over much of the eastern portion of the CWA. Then, during Thursday afternoon, another round of active convection is expected from the interior into the northwestern municipalities. A similar pattern is anticipated on Friday.

Overall, for the remainder of the short-term forecast (Thursday and Friday), the trough will meander over the area and combine with above-normal moisture. With this setup, strong thunderstorms are likely, capable of producing heavy rain, frequent lightning, and gusty winds each afternoon across the northwestern quadrant. Keep in mind that soils are saturated and streamflows remain elevated, therefore, any additional persistent heavy rainfall will maintain an elevated flooding risk each day.

LONG TERM(Saturday through Wednesday)

Issued at 327 AM AST Wed Apr 15 2026

Variable conditions may persist through the weekend, with a gradual improvement over the first part of the next workweek. Wind pattern will mostly be dominated by a surface high pressure lingering over the Central Atlantic, promoting winds from the E-SE. Another feature that may influence the weather pattern in the deep-layered trough that, according to the latest model guidance, is expected to linger over Hispaniola. From the deterministic guidance of the GFS and ECMWF, it seems that Saturday and Sunday will most likely be the wettest days of the period, with PWAT values lingering between 1.8 and 2.0 inches, wet for this time of the year. Additionally, low to mid level moisture content will remain high (above 60%), while model sounding suggests skinny profiles. Conditions look favorable for convection, as the influence of the trough will maintain slightly cooler than normal mid level temperatures (around -8 degrees Celsius) and a nearby jet with strong winds aloft (around 60 knots), allowing cloud growth and ventilation. With the favorable side of the trough over the CWA, divergence aloft will also increase the chance of deeper convection, particularly over western Puerto Rico and the U.S. Virgin Islands. Hence, for the U.S. Virgin Islands, showers and isolated thunderstorms will likely move occasionally throughout the day, while interior and western Puerto Rico can expect showers and thunderstorms in the afternoon that may persist into the evening. Due to previous rainfall activity, soil saturation, and high river levels, the potential for flooding may increase. Hence, the flooding threat will remain limited to elevated for the aforementioned areas. Besides flooding, expect gusty winds and lightning across these areas. For the rest of the areas, passing showers may move from time to time, though a significant flooding threat is not expected. Weather conditions will gradually improve Monday onwards, as moisture content may decrease and the subsident side of the trough moves over the CWA. Nevertheless, theres uncertainty between global solutions as GFS continues with a wet pattern (above normal PWAT) while the ECMWF on the side is moving toward a more seasonal to drier pattern. From the latest grand ensemble, theres variability between them (PWAT difference of half an inch), particularly in the mid to high level moisture content. At the moment, expect a seasonal weather pattern, with isolated showers moving over windward sections in the morning hours, with afternoon convection over interior and western Puerto Rico. Due to the uncertainty, the flood threat will remain limited.

AVIATION

(18Z TAFS) Issued at 225 PM AST Wed Apr 15 2026

VFR condt across most TAF sites, except TJBQ where periods of MVFR condt are possible from 15/18Z-15/22Z with the SHRA/TSRA. Winds will remain light 5-10kt with higher gusts through 15/22Z. Variable winds after 16/03Z and increasing after 16/12Z.

MARINE

Issued at 225 PM AST Wed Apr 15 2026

A surface high pressure system over the eastern to central Atlantic, interacting with surface trough, will promote gentle to moderate from the east-southeast. Pulses of northerly swell spreading across the Atlantic waters are maintaining seas around 5 to 6 feet across exposed areas, where small craft should exercise caution over the next several days. The combination of the front and the trough is increasing showers and thunderstorms across the local waters, creating locally hazardous marine conditions through at least the rest of the workweek.

BEACH FORECAST

Issued at 225 PM AST Wed Apr 15 2026

A High Rip Current Risk is in effect for the northwestern, northern, and eastern exposed beaches of Puerto Rico and Culebra through 6 PM due to the arrival of pulses of a weak northerly swell. Beachgoers are urged to heed the advice of lifeguards, as well as beach patrol flags and posted signs. Elsewhere, a low to moderate risk of rip currents will persists. Increasing winds from midweek onward could lead to a moderate risk of rip currents persisting along north- exposed beaches through at least next Saturday. Residents and visitors are encouraged to exercise caution, especially along exposed coasts. For more specific area details, refer to weather.gov/beach/sju.

SJU WATCHES/WARNINGS/ADVISORIES

PR...High Rip Current Risk until 6 PM AST this evening for PRZ001-002- 005-008-010-012.

VI...None. AM...None.