textproduct: San Juan

KEY MESSAGES

Updated at 214 PM AST Fri Apr 17 2026

* A wet pattern will persist through much of the forecast period, which, combined with local effects, will promote showers and thunderstorms producing flooding rains across portions of PR each day.

* Showers embedded in the trade will move across the USVI each day, resulting in occasional ponding of water in roads and poorly drained areas, and isolated thunderstorms downwind of the islands each afternoon.

* Beachgoers can expect a moderate risk of rip currents along north and east-facing beaches throughout the forecast period in PR and the USVI.

Short Term(This evening through Sunday)

Issued at 214 PM AST Fri Apr 17 2026

In general, we observed calm weather across the USVI and PR in the morning. However, we detected some thunderstorms across the regional waters. Then, rainfall began to affect the USVI, but this activity was brief. In PR, thunderstorms formed downwind from El Yunque into the San Juan Metro Area. Then, the activity moved across western PR, where Flash Flood Warnings were issued. The winds were mainly from the east-southeast at 10 to 20 mph, with sea-breeze variations. Maximum temperatures were in the mid- to upper 80s.

A lingering mid- to upper-level trough, along with above-normal moisture, will create an unstable and wet weather pattern in the short term. Soils are already saturated, and river levels are elevated; therefore, any additional heavy rainfall could quickly result in urban flooding, small stream flooding, river flooding, and flash flooding.

Periods of showers and thunderstorms will occur in pulses rather than continuously. For example, activity is expected this afternoon across western and interior Puerto Rico, while the USVI may see variable cloudiness with occasional showers. The residents in western PR are encouraged to exercise caution, as between 1 and 3 inches of rain with locally higher amounts have fallen at the time of this discussion, and rivers will respond later this afternoon or evening, with minor flooding likely to worsen later this afternoon, especially across the areas under warning. Another round of showers and thunderstorms is possible this evening, particularly across eastern Puerto Rico and possibly the USVI, followed by additional activity early Saturday morning.

On Saturday and Sunday, a similar convective pattern will form, especially in the afternoon across the interior and western PR, with additional rounds during the evening and morning hours. Although the USVI will remain under the influence of high moisture and the upper-level trough, confidence remains low regarding rainfall coverage and intensity.

Residents and visitors are urged to remain alert and monitor official forecasts, advisories, and warnings as conditions evolve.

LONG TERM(Monday through Friday)

Issued at 250 AM AST Fri Apr 17 2026

The forecast remains on track with no significant changes from the previous discussion. As the influence of the upper-level trough weakens and exits the northeastern Caribbean, drier and more stable conditions are expected to return. A mid-level ridge will build over the area, bringing a stable air mass aloft. At the surface, a dominant high pressure system over the central Atlantic will maintain light to moderate easterly winds through mid-week. During the first half of the period, precipitable water (PWAT) values will drop to seasonal normals of approximately 1.50 inches and are expected to remain within that range for the rest of the workweek.

Local conditions will stay seasonal, with occasional showers moving into the eastern portions of Puerto Rico, Vieques, Culebra, and the U.S. Virgin Islands during the morning hours. This will be followed by afternoon convective activity across the interior and western portions of Puerto Rico. This afternoon activity could result in moderate to heavy rainfall and isolated thunderstorms due to the combination of available moisture, daytime heating, and local effects. Temperatures at 500 mb are expected to remain within seasonal values of -6C to -8C; therefore, a thunderstorm or two cannot be ruled out. Due to previous rainfall, soil saturation, and elevated river levels, the potential for flooding persists. Temperatures at 925 mb will remain seasonal through most of the period, with highs in the low to mid-80s across coastal and urban areas and the upper 70s to low 80s in the higher mountains.

AVIATION

(18Z TAFS) Issued at 214 PM AST Fri Apr 17 2026

Mainly VFR conditions are expected across TAF sites with the exception of SHRA & TSRA from 17/18Z thru 17/22Z that could result in intermittent MVFR to brief IFR conds across TJBQ. E winds at around 10 to 15 kts with gusts around 18 to 25 kts and sea breeze variations, becoming lighter overnight and increasing again around 18/13Z onward along with SHRA/TSRA aft 18/16Z.

MARINE

Issued at 214 PM AST Fri Apr 17 2026

A mid to upper-level trough will maintain an unstable weather pattern across the regional waters, resulting in periods of strong thunderstorms through at least Saturday. Thunderstorms will produce locally higher winds, frequent lightning, and reduced visibility. A surface high over the Atlantic will promote mainly moderate easterly winds, occasionally fresh at times, resulting in moderate to locally choppy seas over the weekend. A small northeasterly swell will also continue to propagate across the Atlantic waters and Caribbean passages through early next week.

BEACH FORECAST

Issued at 214 PM AST Fri Apr 17 2026

A moderate risk of rip currents is present along the north-facing beaches of Puerto Rico, Culebra, and the U.S. Virgin Islands this afternoon and tonight. This means that life-threatening rip currents are possible in the surf zone. This pattern is expected to persist through the weekend and into early next week. Beachgoers are encouraged to remain cautious in these exposed areas. Meanwhile, along southern coastlines, a low risk is present. However, keep in mind that life-threatening rip currents often occur near groins, jetties, reefs, and piers, even when the overall risk is low.

Another beach hazard is the development of thunderstorms each afternoon, particularly along the western and northern beaches of Puerto Rico. Remain weather-aware due to rapidly changing conditions, and be prepared to seek shelter if you hear thunder.

A long-period northerly swell may arrive by midweek next week, slightly deteriorating coastal conditions. Stay tuned to the forecast.

SJU WATCHES/WARNINGS/ADVISORIES

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