textproduct: San Juan

KEY MESSAGES

Issued at 438 AM AST Tue Dec 2 2025

* There is a moderate risk of life-threatening rip currents along the north and east-facing beaches in PR and the US Virgin Islands today and through much of the forecast period.

* We have a slight risk of thunderstorms, especially in the interior and mountain areas of PR, St. Thomas, and St. John this afternoon.

* St Thomas, St John, and the mountain areas in PR have a slight risk of flooding rains this afternoon into the evening.

* Residents and visitors in the US Virgin Islands and the windward portions of Puerto Rico can expect occasional passing showers each day.

Short Term(Today through Thursday)

Issued at 438 AM AST Tue Dec 2 2025

Overnight hours remained relatively tranquil, with most showers staying over the surrounding waters. Temperatures stayed in the 70s along coastal areas and in the 60s across the higher terrains. Winds were light and variable across Puerto Rico and the U.S. Virgin Islands.

The latest precipitable water models continue to show near-seasonal moisture values over the local area, with slightly higher PWATs to the northeast in association with an induced surface trough. Model guidance favors this trough gradually drifting across the islands over the next couple of days, weakening the prevailing NEE flow and allowing deeper moisture to pool across the region. At the same time, 500 mb temperatures are forecast to drop to around 9 degrees Celsius, falling below the 25th percentile for this time of year. Cooler mid-levels, combined with higher moisture and favorable upper- level ventilation, will support a more unstable environment. As a result, deeper cloud development and a vertical development in showers and isolated thunderstorms are expected, particularly during the afternoon when daytime heating maximizes convective growth. Current guidance highlights today as the most active day in the short-term period. Nevertheless the wet pattern should prevail through Thursday. Weakening winds will also increase the likelihood that any showers or thunderstorms that form move slowly or remain nearly stationary. If that occurs, localized flooding could develop, especially across the eastern half and interior sections of Puerto Rico. Although model guidance support rainfall amounts capable of producing minor flooding impacts, confidence remains limited due to uncertainty in cloud cover. If widespread clouds develop early, daytime heating and resulting convection may be weaker than the rainfall signals suggest. For this reason, flooding potential is present but remains under the limited threshold.

A similar pattern is anticipated on Wednesday, with afternoon convection possible, though current model trends point to somewhat lower coverage and intensity than what is expected today and Thursday. Also models indicates a slight increase in 925 mb temperatures through mid-week, with Wednesday likely being the warmest day. While localized heat indices may briefly approach 100 F, probabilities keep values below Heat Advisory criteria. As a result, no significant heat-related impacts are anticipated during the forecast period.

Long Term(Friday through Tuesday)

Issued at 438 AM AST Tue Dec 2 2025

A mid- to upper-level ridge building from the west over the northeast Caribbean will likely displace a trough aloft eastward and away from the region by Friday, promoting a more stable atmosphere. This ridge aloft is expected to build and persist throughout the forecast period, supporting subsidence and dry air aloft, and reinforcing the trade-wind inversion.

With this pattern in place, an advective trade-wind regime will prevail. As a result, there is a low (10-20%) to moderate (30-50%) chance of occasional passing showers across the windward areas of Puerto Rico and the US Virgin Islands each day. Afternoon convection across the interior and western Puerto Rico also carries a low to moderate chance of developing daily, but current guidance does not indicate a flooding threat at this time.

Overall, expect a mix of sunshine and clear skies with periods of passing clouds. Windward locations can anticipate occasional brief showers carried by the prevailing trades.

AVIATION

(06Z TAFS) Issued at 438 AM AST Tue Dec 2 2025

VFR conditions are expected to prevail across all TAF sites. Brief periods of MVFR are possible after 17Z at TJSJ, TIST, and TJPS due to increasing afternoon shower and thunderstorm activity. Winds will remain light from the NE, with occasional higher gusts near any stronger shower activity. After 02/17Z, VCTS, VCSH and -RA will be possible at TJSJ, TIST, and TJPS mainly associated with slow-moving convection.

MARINE

Issued at 438 AM AST Tue Dec 2 2025

A surface trough northeast of the islands will promote moderate northeasterly winds today, then winds will shift more from the southeast to south tonight into Wednesday, as the trough moves westward near the region. Afternoon thunderstorms will form the next few days due to the proximity of the surface trough. A small easterly swell will spread across the local waters through Thursday. Additionally, a surface high pressure across the Central Atlantic will promote the return of the moderate to locally fresh east to northeast winds the second part of the week.

BEACH FORECAST

Issued at 438 AM AST Tue Dec 2 2025

A small easterly swell will promote a moderate risk of rip currents along the north and east facing beaches of Puerto Rico, including Vieques and Culebra, and across the U.S. Virgin Islands. These conditions will persist most of the week due to the small easterly to northeasterly swell and increasing winds from Thursday onward. A moderate risk means that life-threatening rip currents are possible and can quickly pull swimmers away from shore.

Even where the risk is lower, rip currents can still form near groins, jetties, reefs, and piers. Visitors and residents are strongly encouraged to swim near a lifeguard and remain aware of changing conditions.

There is a slight risk of thunderstorms, especially during the afternoon hours, across western Puerto Rico. This activity could move across coastal areas at times, increasing the risk of lightning strikes.

SJU WATCHES/WARNINGS/ADVISORIES

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