textproduct: San Juan

KEY MESSAGES

Updated at 221 PM AST Fri Apr 10 2026

* A High Risk of Rip Currents is in effect for the northern coast of Puerto Rico and Culebra through late Sunday due to a long- period, northwest to northerly swell.

* Mainly fair weather conditions will prevail today through at least Saturday, with isolated showers over eastern Puerto Rico and the U.S. Virgin Islands and afternoon convective activity over central and western Puerto Rico.

* An approaching mid to upper level trough will result in a wetter and more unstable pattern with an increased flooding risk as it reaches the islands late Sunday into the next workweek.

Short Term(This evening through Sunday)

Issued at 222 PM AST Fri Apr 10 2026

Very calm weather conditions prevailed today under mostly clear to partly cloudy skies. Satellite and radar observations showed a few showers moving into the eastern portions of Puerto Rico and the northern U.S. Virgin Islands during the morning hours; however, rainfall accumulations were minimal. It was another warm day across the region, with highs reaching the upper 80s to lower 90s along coastal and urban areas, while temperatures stayed in the low to mid- 80s in the higher mountains. The Luis Munoz Marin International Airport in San Juan observed a high of 88F, which is 2F above the average temperature for April 10th. Heat indices climbed above 100F, particularly over the north-central region of Puerto Rico.

For the rest of the day, calm conditions are expected to continue across the region. Nonetheless, a few showers may develop across western Puerto Rico due to daytime heating and local effects. Similar conditions should prevail on Saturday as a mass of drier air filters into the area. East-southeast winds will persist, driven by a broad surface high dominating the central Atlantic, with precipitable water values remaining around 1.50 inches.

From Sunday afternoon onward, an increase in moisture is anticipated, with precipitable water values exceeding 2.00 inches as a mid-to-upper level trough approaches the northeastern Caribbean. Consequently, the end of the weekend will serve as a transition from a relatively dry pattern to a wetter, more unstable forecast. This shift will likely bring an increase in shower frequency to eastern Puerto Rico and the U.S. Virgin Islands during the morning, followed by enhanced afternoon showers and thunderstorms.

These conditions will enhance the potential for flooding across the area. The mid-to-upper level trough is expected to move over Puerto Rico and the U.S. Virgin Islands by early Monday, elevating the risk of urban and small stream flooding, as well as rapid river rises. While a brief break in rainfall this weekend may allow for some drying, soils remain saturated across eastern and southern Puerto Rico. Currently, most streams are running at normal to high levels across the region. Residents and visitors are encouraged to monitor weather updates throughout the weekend as conditions evolve. Please refer to the latest Hydrologic Outlook (ESFSJU) for additional details.

Long Term(Monday through Friday)

Issued at 457 AM AST Fri Apr 10 2026

A wetter and more unstable pattern will develop Monday and persist through midweek as a deep-layered trough and developing upper-level low remain northwest of the region, supporting favorable divergence aloft through at least Tuesday night. Deep moisture will surge into the area from the east on Monday, with precipitable water values exceeding climatological maxima before organizing into a moisture band that lingers over the region Tuesday into Wednesday, then gradually shifts southwestward into the Caribbean by Thursday. Low- level winds will veer from EENE Monday to ESE by midweek, supporting a transition from a more typical diurnal pattern early Monday to increasingly widespread and organized convection Monday afternoon through at least Tuesday, and possibly into Wednesday. Cooler temperatures aloft through Tuesday night will enhance instability, followed by gradual warming by Wednesday into Thursday, leading to a slow decrease in convective intensity, although a moist column will persist.

The primary concern is an elevated to locally significant flooding risk, increasing Monday afternoon and peaking Tuesday into Wednesday. Periods of heavy and repeated rainfall may result in urban and small stream flooding, isolated flash flooding, and localized landslides or rapid river rises. Slower storm motion, particularly on Tuesday, could enhance rainfall totals in affected areas. Model guidance has been consistent in highlighting this event, including the ECMWF Extreme Forecast Index, which indicates anomalously high rainfall potential building Monday, peaking Tuesday into Wednesday, and diminishing by Thursday. Although activity should become less organized late in the period, above-normal moisture will continue to support scattered showers with localized impacts. Confidence is moderate to locally high in the overall pattern, though some uncertainty remains in the exact placement of the heaviest rainfall.

For additional details, including rainfall expectations and hydrologic conditions, refer to the Hydrologic Outlook (ESFSJU).

AVIATION

(18Z TAFS) Issued at 222 PM AST Fri Apr 10 2026

Mainly VFR conds are expected across TAF sites this forecast period. The site with the greater chance to observe SHRA & VCSH is TJBQ from 11/18Z thru 11/22Z. This could result in intermittent periods of MVFR conds due to lower cigs and reduced vis. Winds will continue mainly from the ESE at around 10 to 15 kts and gusts around 20 to 23 mph and sea breeze variations. Lighter winds returning aft 11/23Z with increasing potential of VCSH across eastern TAF sites.

MARINE

Issued at 222 PM AST Fri Apr 10 2026

As a broad surface high pressure system builds over the central Atlantic, winds have become more easterly and will persist from that direction through the weekend. A 4- to 5-foot northwest to northerly swell will spread across the Atlantic waters and local passages, building seas up to around 6 feet over the next few days. Therefore, small craft should continue to exercise caution, especially over the Atlantic waters.

Another pulse of northerly swell is expected on Sunday. By early next week, a frontal boundary and a pre-frontal trough will increase showers and thunderstorms across the regional waters. Winds will also strengthen from moderate to locally fresh, with seas building up to around 7 feet. As a result, Small Craft Advisories may be issued for the Atlantic waters during this upcoming period.

BEACH FORECAST

Issued at 222 PM AST Fri Apr 10 2026

A 4 to 5 foot long-period northwest to northerly swell will gradually spread across the Atlantic waters and local Caribbean passages today. The latest San Juan buoy observations show seas of around 5 feet with periods of 11 to 12 seconds, which should result in breaking waves of approximately 6 to 7 feet. This will maintain a high risk of life-threatening rip currents along the north-facing beaches of Puerto Rico and Culebra, where a High Rip Current Risk remains in effect through the weekend. By early Sunday, another pulse of northerly swell is expected to reach the northern exposed coastal waters.

Across the USVI and Vieques, a moderate risk of rip currents is expected to persist over the next several days, while a low risk will continue along the southern and more protected beaches. More information is available at weather.gov/beach.sju.

SJU WATCHES/WARNINGS/ADVISORIES

PR...High Rip Current Risk through Sunday afternoon for PRZ001-002- 005-008.

High Rip Current Risk through Saturday afternoon for PRZ012.

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