textproduct: San Juan

KEY MESSAGES

Issued at 240 PM AST Wed Apr 1 2026

* Large breaking waves and life-threatening rip currents will continue along north and east-facing beaches tonight and tomorrow. Stay out of the water.

* Choppy to rough seas will result in hazardous conditions for small craft, persisting over the weekend. Small Craft Advisories remains in effect.

* Showers and isolated thunderstorm will continue in the afternoon over interior and southern Puerto Rico, leading to ponding of water over roadways and poorly drained areas.

* Breezy to locally windy conditions expected across coastal areas of the islands through early next week.

Short Term(This evening through Friday)

Issued at 240 PM AST Wed Apr 1 2026

A surface high over the Atlantic will continue to promote up to breezy ENE flow during the period as well as steer patches of moisture towards the region. Current satellite-derived precipitable water (PWAT) values indicate a patch of moisture of around 1.6 inches over the Atlantic waters and approaching the islands. Diurnal heating, along with the ENE flow have will continue to result in the development of showers and isolated t-storms over the Cordillera towards south-central, southwestern and western PR, as well as showers over the northern USVI towards Culebra and eastern Puerto Rico and mainly downwind of Vieques. This will result in a limited flooding risk over mainly the southwestern quadrant of Puerto Rico. Although these afternoon showers will gradually dissipate and/or move offshore, the above mentioned patch of moisture over the Atlantic will result in an increase in passing shower activity over windward sectors late tonight as this air mass moves over the region. Afternoon convection is once again forecast tomorrow, Thursday, for similar areas as today due to diurnal heating and local effects but with more E to ENE steering flow possibly steering showers towards western PR as well. A limited flooding risk continues. Moisture is expected to deepen and become more established from tomorrow, Thursday, night into Friday. This setup will lead to more frequent passing showers across the eastern and northern parts of Puerto Rico and the U.S. Virgin Islands under ENE flow. The highest rainfall totals will be a result of afternoon convection each day over mainly interior to W, SW and S-Central PR depending on the steering flow. Shower and isolated t-storm development will be favored due to the combination of a nearby upper- level trough and the lack of a well-defined trade wind cap. A limited flooding risk will continue each day (especially late tomorrow onwards) resulting in ponding of water in roads and poorly drained areas and possible urban and small streams flooding. PWAT values are forecast at normal to high-end normal values while 925 mb wind speeds will be at 15-20 kts throughout the shower term period, promoting quicker moving showers. 925 temperatures will be below normal throughout the short term period. Highs will be in the 80s across coastal areas of the islands with isolated sectors at around 90, lows will be in the upper 60s to low 70s across coastal areas of the islands and in the upper 50s to lower 60s at higher elevations of Puerto Rico.

Long Term(Saturday through next Tuesday)

Issued at 200 AM AST Wed Apr 1 2026

For the beginning of the long-term period, a weather pattern influenced by an induced surface trough and an upper-level shortwave trough is expected. This combination will lead to increasingly unstable conditions across the islands. As the disturbance moves west of the region, its interaction with a high-pressure system over the Central Atlantic will promote an east-southeasterly wind flow.

The upper-level trough will enhance instability and support thunderstorm development, resulting in a high probability of showers. However, a deep upper-level cloud layer may limit daytime heating, potentially reducing widespread activity. Even so, localized, well-developed showers are expected, especially across northwestern areas and the San Juan metro region. By Sunday, precipitable water values are forecast to reach around 1.7 inches, near the 75th percentile for this time of year. A limited to elevated flood risk will persist each afternoon. As a result, similar conditions are expected on Sunday, as the upper-level trough continues to influence the region along with periods of enhanced cloud cover. During this time, a limited to elevated flood risk will persist each afternoon.

From Monday through Wednesday, the surface pattern will become dominated by a broad high-pressure system over the Central Atlantic, resulting in southeasterly winds. During this period, increasing low- level moisture from the Caribbean will spread across the islands, with precipitable water values rising to around 1.9 inches and remaining near the 75th percentile, based on climatological data for this time of the year. With weaker upper-level dynamics, cloud cover aloft will be less extensive, allowing for more effective daytime heating. As a result, afternoon convection is expected to become more widespread and better organized, particularly across western and interior Puerto Rico, where local effects will enhance shower and thunderstorm development. This pattern, combined with warm and humid conditions, will increase the risk of urban and small stream flooding.

AVIATION

(18Z TAFS) Issued at 240 PM AST Wed Apr 1 2026

Mainly VFR conditions through the period. Brief MVFR conditions are possible mainly at TJPS and TIST as -SHRA and ,for TJPS, VCTS develops through around 01/22z. VCSH/-SHRA reaching mainly northern sites from the Atlantic under ENE flow. ENE winds at 12 to 18 kts with higher gusts through this evening, with 8 to 14 kts overnight, and increasing again after 02/13Z. VCSH/-SHRA reaching mainly northern sites from the Atlantic under ENE flow.

MARINE

Issued at 240 PM AST Wed Apr 1 2026

Hazardous marine conditions will persist through the week under a strong Atlantic high-pressure system. Fresh to strong northeasterly winds and a persistent north-northeasterly swell will maintain choppy to rough seas across regional waters, with conditions continuing even as winds shift easterly by the end of the week. Frequent trade wind showers will move across the Atlantic waters and local passages, with isolated afternoon thunderstorms possible over the Caribbean waters that may produce lightning. Small Craft Advisories remain in effect for northern and exposed waters through at least Saturday.

BEACH FORECAST

Issued at 240 PM AST Wed Apr 1 2026

Some changes were introduced to the beach forecast. Current nearshore buoys are reporting seas between 6 and 8 feet and a period of around 11 seconds, resulting in breaking waves between 12 and 14 feet. NDBC buoy 41043 continues to report seas between 11 and 14 feet, with a dominant period around 11 - 13 seconds. This energy, expected to arrive tonight, will very likely lead to large breaking waves (between 10 and 13 feet, occasionally higher) over exposed beaches in the northern areas of the islands. Additionally, the swell direction is gradually shifting, becoming from the north- northeast, and based on the latest guidance, winds will gradually strengthen starting this afternoon. Given the current conditions and the expected forecast, the High Surf Advisory has been extended for the northern and eastern beaches of Puerto Rico, including Vieques and Culebra, and the U.S. Virgin Islands through 6 PM AST Thursday. Beachgoers and inexperienced surfers are urged to avoid going into the water, walking over rocks or jetties, as large breaking waves pose a life-threatening risk. Heed the advice of lifeguards, beach patrol flags, and signs. Additionally, these conditions could result in localized beach erosion over vulnerable areas. The Rip Current remains in effect through late Friday night, though it will likely be extended as life-threatening rip currents may persist in the upcoming weekend.

Besides rip currents and high surf conditions, beachgoers should stay weather alert due to showers and isolated thunderstorms in the afternoon that may produce lightning over the western coastal areas of Puerto Rico. Seek shelter inside a building whenever you hear lightning.

SJU WATCHES/WARNINGS/ADVISORIES

PR...High Rip Current Risk through late Friday night for PRZ001-002- 005-008-010-012-013.

High Surf Advisory until 6 PM AST Thursday for PRZ001-002-005- 008-010-012-013.

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

High Surf Advisory until 6 PM AST Thursday for VIZ001-002.

AM...Small Craft Advisory until 6 AM AST Saturday for AMZ711-712-716- 723-741-742.

Small Craft Advisory until 6 AM AST Friday for AMZ726.