textproduct: San Juan

KEY MESSAGES

Updated at 206 PM AST Sun May 3 2026

* Isolated to scattered showers are possible over northwestern Puerto Rico during the afternoon hours, mainly fair weather prevailing elsewhere.

* Fair weather conditions are expected to continue over the next few days, with just locally induced afternoon showers over western Puerto Rico.

* Warmer-than-normal temperatures will persist, with heat indices reaching or exceeding 100 degrees F across urban and coastal areas.

* A moderate risk of rip currents will continue through at least Thursday along the north and east-facing beaches of Puerto Rico, Culebra, and the U.S. Virgin Islands at times.

Short Term(This evening through Tuesday)

Issued at 206 PM AST Sun May 3 2026

The primary weather hazard through Tuesday will be above-normal temperatures. With 925mb temperatures reaching the 75th percentile of climatology (2123C), daytime highs will climb into the upper 80s to low 90s across coastal and urban areas. Combined with existing humidity, heat indices are expected to reach or exceed 100F.

A strengthening mid-level ridge and a prevailing east-to- southeasterly trade wind flow will dominate the weather pattern through the short-term period. The latest 12z sounding data show a relatively dry air mass, with Precipitable Water (PWAT) near 1.40 inches, which is on the lower end of seasonal climatology. Mid- level relative humidity (700-500mb) remains limited at approximately 3045%, while a persistent trade wind cap near the 850mb level will act to suppress widespread deep convection. Therefore, the expected locally induced afternoon showers over northwestern PR will leave mostly minor rainfall accumulations.

Similar conditions will continue through Monday, as fair weather will prevail across the islands. However, daytime heating and local sea breeze convergence will likely trigger isolated scattered afternoon showers, primarily over the interior and northwestern sections of Puerto Rico. For the USVI and eastern windward coasts of Puerto Rico, expect brief, shallow trade wind showers during the overnight and early morning hours.

Model guidance suggests a subtle surge of low-level moisture (PWAT near 1.60 inches) on Tuesday. While significant rainfall is not anticipated, this surge in moisture may lead to increased coverage of passing showers across windward areas and a slightly more active afternoon in western Puerto Rico.

Long Term(Wednesday through next Saturday)

Issued at 410 AM AST Sun May 3 2026

An upper level trough will cross the local islands on Wednesday, causing mid-levels temperature to cool down. Although this would usually result in an increase in instability, a mid-level ridge will maintain conditions generally unfavorable for strong showers production. Later in the workweek, a cold front at the mid-levels will cross the region. The air mass will dry out further, with the forecast soundings suggesting considerable dew point depressions and trade wind caps around 850 mb levels. In general, fair weather will prevail, but diurnal heating should still trigger localized convection in the interior and west of Puerto Rico. Also, patches of moisture trapped in the lower 850 mb of the atmosphere will be dragged by the trade winds along the Virgin Islands and eastern Puerto Rico at times. However, the risk of flooding will be low to none for most of the period.

The steering flow at the surface will be mainly out of the east at around 10 knots through much of the forecast period. Aloft, winds will be from the north, but this will not translate into cooler temperatures. Highs will still reach the upper 80s and low 90s along many coastal areas, and around 80 in the mountain.

In comparison with the previous cycles, the probability of precipitation has been decreased for most of the period. By the next weekend however, the mid level ridge will lose its grip a little, as a mid to upper level low develops northeast of the Caribbean. Stronger showers and isolated thunderstorms are expected to form, mostly focusing along the interior and western Puerto Rico.

AVIATION

(18Z TAFS) Issued at 206 PM AST Sun May 3 2026

Mainly VFR conditions are expected to prevail across all terminals during the next 24 hours. The 03/12z TJSJ sounding indicated ESE winds up to 21 kt blo FL050. Winds will become light and variable overnight.

MARINE

Issued at 206 PM AST Sun May 3 2026

A broad area of high pressure over the central Atlantic will support gentle to moderate east to east-southeast flow across most of the local waters through much of the forecast period. Seas are expected to range from 3 to 5 feet, occasionally building to around 6 feet, due to a mix of locally generated wind waves and a weak, long-period northeasterly swell. Isolated showers could briefly enhance winds and seas at times.

BEACH FORECAST

Issued at 206 PM AST Sun May 3 2026

Tonight, a moderate risk of rip currents will persist along the north and east-facing beaches of Puerto Rico, including Culebra. This indicates that life-threatening rip currents are possible in the surf zone, and beachgoers should exercise caution. A similar pattern is expected to continue through at least Thursday, with the U.S. Virgin Islands included at times as pulses of a small, long- period northeasterly swell promote higher breakers and stronger rip currents along north-exposed areas.

By late week, conditions are expected to gradually improve, with a low risk briefly prevailing across most beaches. For additional information and location-specific rip current details, visit weather.gov/beach/sju.

SJU WATCHES/WARNINGS/ADVISORIES

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