textproduct: San Juan

KEY MESSAGES

Updated at 300 AM AST Sun Apr 5 2026

* An unsettled and moist weather pattern will persist across Puerto Rico and the U.S. Virgin Islands through at least midweek, supporting an elevated to locally significant risk of flooding each afternoon and evening.

* Thunderstorms are expected to develop daily, producing gusty winds and frequent lightning.

* Breezy to locally windy conditions will continue, enhancing moisture transport across the region.

* Additionally, life-threatening rip currents will persist along the north- and east-facing beaches of the archipelagos of PR and the USVI.

* Warmer-than-normal temperatures will develop by midweek, with heat indices potentially reaching the low 100s.

Short Term(Today through Tuesday)

Issued at 300 AM AST Sun Apr 5 2026

Fair weather prevailed today across the islands, with passing showers over the local waters and moving inland across the windward sections, especially across southeast PR and the USVI. The east-southeasterly winds were mainly at 10 mph or less, with land-breeze variations, especially along the leeward sections. Most coastal and urban sites recorded minimum temperatures in the low or mid-70s, while mountain sites recorded minimum temperatures in the low 60s.

A surface high-pressure system building across the western to central Atlantic will maintain an east-to-east-southeast wind flow across the islands, resulting in breezy to locally windy conditions. Embedded within this flow, patches of moisture will continue to move across the region, promoting passing trade wind showers across windward sectors of Puerto Rico and the U.S. Virgin Islands during the overnight and early morning hours. By late morning into the afternoon, diurnal heating, local sea breeze convergence, and orographic effects will favor the development of convection across the interior and western portions of Puerto Rico, with activity potentially spreading into surrounding coastal and urban areas.

A mid- to upper-level trough will enhance atmospheric instability across the region, while model guidance indicates near- to above- normal precipitable water values. This combination will support an active convective pattern each day. As a result, a limited to elevated risk of flooding rains will persist, particularly during the afternoon and evening hours across interior, western, and eastern Puerto Rico, as well as portions of the northern U.S. Virgin Islands. Although periods of fair weather with partly sunny skies are expected at times, the prevailing breezy pattern and sustained moisture advection will maintain favorable conditions for shower and thunderstorm development. Isolated thunderstorms may produce frequent lightning and locally gusty winds.

Long Term(Wednesday through Sunday)

Issued at 300 AM AST Sun Apr 5 2026

The current forecast remains on track, with a period of wet and unstable weather across Puerto Rico and the U.S. Virgin Islands. This pattern is driven by a mid-to-upper-level trough approaches from the west and settles over the northeastern Caribbean. At the surface, an induced inverted trough near Hispaniola will maintain a persistent southeasterly wind flow, pulling deep tropical moisture into the region. Precipitable water (PWAT) values are forecast to reach 2.00 to 2.20 inches by Wednesday, well above climatological normals.

Combined with above-normal temperatures at the 925 mb level, this setup could drive heat indices into the low 100s for the first time this year, a trend that may persist through the weekend. Furthermore, cooler mid-level temperatures ranging from -8C to -9C will likely enhance convective instability, leading to intense thunderstorms and frequent lightning.

Daily widespread rainfall and thunderstorms are anticipated, particularly during the afternoon hours across central, northern, and northwestern Puerto Rico, including the San Juan metro area. This activity will be enhanced by diurnal heating and local effects. The most active period is expected on Wednesday and Thursday, bringing a high risk of: heavy rainfall, gusty winds, frequent lightning, rapid river rises, potential landslides and urban and small stream flooding, especially in areas with saturated soil. In contrast, the U.S. Virgin Islands will likely experience only occasional passing showers with minor impacts during this timeframe.

Conditions are expected to improve by Friday as the trough weakens and departs the area. While lingering moisture may trigger isolated or scattered showers, the overall intensity and coverage will diminish. From Saturday onwards, the region will transition back to a more stable weather pattern, characterized by passing trade wind showers and typical afternoon convection over central and western Puerto Rico.

AVIATION

(06Z TAFS) Issued at 300 AM AST Sun Apr 5 2026

VFR conds will prevail, but MVFR/brief IFR may occur due to passing SHRA/+SHRA/TSRA. Eastern terminals like TJSJ/TIST/TISX will experience trade wind SHRA, especially in the morning and evening. Afternoon convection will mainly affect interior and W terminals, such as TJBQ. Winds will be calm-light/VAR until 5/13Z, then shift to ESE at 10-20 kt, with higher gusts near convection. Be aware of mountain obscuration, reduced visibility in heavy rain, and isolated lightning.

MARINE

Issued at 300 AM AST Sun Apr 5 2026

Hazardous marine conditions are expected to persist through early this week. A strong high-pressure system over the Atlantic will maintain moderate to fresh east-southeasterly winds today, and this pattern will persist through most of the period. When combined with a fading northeasterly swell, seas will remain choppy to rough, particularly across Atlantic waters and local passages. While trade wind showers continue across the region, isolated to scattered thunderstorms are expected, especially during the afternoon hours over coastal waters, particularly near western and northwestern Puerto Rico. Coverage may increase slightly throughout the week as a series of nearby troughs interact with abundant tropical moisture.

BEACH FORECAST

Issued at 300 AM AST Sun Apr 5 2026

A high risk of rip currents (life-threatening rip currents are likely in the surf zone) continues for the northern and eastern coastlines of Puerto Rico, Vieques, Culebra, and the USVI, though conditions have begun to gradually subside. Breaking waves can still reach to around 7 feet, particularly along the northern coastline of Puerto Rico. This is due to a slowly fading northeasterly swell and breezy to locally windy conditions.

Although hazards will continue to gradually diminish, a high rip current risk will persist for most of these areas through at least Monday. Beachgoers and inexperienced surfers are strongly urged to stay out of the water. A moderate risk of rip currents is expected to develop across some areas by Tuesday, with conditions becoming more hazardous again by midweek through the end of the workweek as another swell impacts the northern shoreline.

Beachgoers and inexperienced surfers should avoid entering the water, especially near rocks or jetties, as life-threatening rip currents remain possible. Heed the advice of lifeguards, beach patrol flags, and posted signs. Access to hazardous beaches may be limited, and individuals should follow all posted warnings and safety guidance.

Visitors should also remain mindful of the weather in addition to surf hazards. Passing showers and isolated thunderstorms may still develop, particularly during the afternoon hours, producing locally gusty winds and brief heavy rainfall. If thunder is heard, seek shelter indoors immediately.

For additional information and location-specific rip current details, please visit: weather.gov/beach/sju.

HYDROLOGY

Issued at 300 AM AST Sun Apr 5 2026

An elevated risk of flooding will persist across the region through at least midweek due to a combination of abundant moisture, atmospheric instability, and recurrent convection. Urban flooding, small-stream flooding, and rapid river rises are possible each afternoon and evening, particularly across interior and western Puerto Rico, as well as in urban and poorly drained areas. The highest risk is expected during the midweek period, when deeper moisture and stronger instability coincide. Localized flash flooding and isolated landslides are also possible in areas with steep terrain and saturated soils. Residents and visitors are urged to remain alert to changing weather conditions and to avoid flooded roadways.

SJU WATCHES/WARNINGS/ADVISORIES

PR...High Rip Current Risk through Monday afternoon for PRZ001-002- 005-008-012.

High Rip Current Risk through late tonight for PRZ010-013.

VI...High Rip Current Risk through Monday afternoon for VIZ002.

High Rip Current Risk through late tonight for VIZ001.

AM...Small Craft Advisory until 6 PM AST Monday for AMZ711.

Small Craft Advisory until 6 AM AST Monday for AMZ712-716-741.

Small Craft Advisory until noon AST Monday for AMZ723.

Small Craft Advisory until noon AST today for AMZ742.