textproduct: San Juan

KEY MESSAGES

Issued at 335 AM AST Thu Nov 13 2025

* Dangerous beach conditions along northern Puerto Rico, Culebra, St. Thomas and St. Croix. Avoid approaching or swimming in these beaches.

* Showers and thunderstorms are expected to develop this afternoon along western Puerto Rico. There is a low risk of urban and small stream flooding.

* For the Virgin Islands, seasonably warm temperatures and passing showers are expected. No significant threat are expected over land areas.

Short Term(Today through Saturday)

Issued at 335 AM AST Thu Nov 13 2025

A variable weather pattern prevailed overnight, with frequent passing showers along the local waters and some reaching the northeast coast of Puerto Rico and the U.S. Virgin Islands. Shower activity remained limited across the interior and western portions of Puerto Rico. Minimum temperatures stayed in the mid-to-upper 70s across the mountain areas, with slightly warmer readings across the coastal zones in the upper 70s to low 80s, including the U.S. Virgin Islands. Winds were from the east at 10 mph or less with land breeze variations.

For today, a variable weather pattern is forecast, mainly influenced by surface high pressure over the Central Atlantic, resulting in easterly winds. This surface flow will keep the islands under a moist pattern due to patches of moisture from an induced surface trough just north of the area, with precipitable water values around 1.6 inches, near climatological normals. With sufficient low-level moisture, local effects, and colder temperatures at 500 MB decreasing from -5 to -6 C, a convective pattern will develop, especially across the western interior. Although widespread activity is not expected, isolated thunderstorms cannot be ruled out. A drying trend is anticipated on Friday as precipitable water values decrease to the 25th percentile, allowing for a calmer weather pattern with isolated showers, particularly during the night hours.

Surface conditions are expected to change rapidly late Saturday as an approaching frontal boundary sinks southward north of the islands, while the pre-frontal trough weakens the pressure gradient. This evolving pattern will result in light and variable winds, as suggested by the 925 MB winds, which are forecast to weaken to near 5 knots. At upper levels, a decrease in 250 MB heights will enhance divergence aloft, supporting upward motion, while the 850700 MB layer will show a spike in moisture values above the normal climatological range. As a result, an increase in shower activity is expected across the offshore Atlantic waters, extending into the northern coastal areas by Saturday afternoon.

Long Term(Sunday through Thursday)

Issued at 335 AM AST Thu Nov 13 2025

A polar trough will escort a cold front near the area on Sunday, increasing moisture across the region. Ahead of the front, high pressure centered over the eastern Atlantic will drive the trade winds from the south at speeds of only 3 to 4 kts. So far, the global models only indicate precipitable water values near normal levels, and also quite a large dew point depression in the mid levels. This means that a widespread rainfall event is not expected. However, some showers will reach the islands at times. Also, the heaviest activity is expected to develop along the interior of Puerto Rico due to local effects.

As the front dissipated north of the region, a short wave trough in the upper levels will move into the region. This will cause mid- levels temperatures to cool down, increasing instability aloft. Moisture levels will not be impressive though, but should be enough to see a few thunderstorms developing each afternoon along the interior and western Puerto Rico. The risk of flooding is low at this time, although isolated urban and small stream flooding cannot be ruled out.

By the end of the week, another trough digs from the northeast. A surface reflection of this trough will change the winds from the northeast, at speeds of 10 to 15 mph. The islands are not expected to be in the most favorable area for deep convection to develop, but the frequency of passing showers could increase for portions of northeast Puerto Rico, as well as for the Virgin Islands.

AVIATION

(06Z TAFS) Issued at 335 AM AST Thu Nov 13 2025

VFR conditions will prevail across all TAF sites during the period. After 13/15Z, winds will increase again from the east at around 15 knots with sea breeze variations. Afternoon showers may lead to lower ceilings and reduced visibility, resulting in brief MVFR conditions at TJBQ and TJPS between 13/17Z and 13/22Z.

MARINE

Issued at 335 AM AST Thu Nov 13 2025

A north-northwesterly swell will continue to arrive today, deteriorating marine conditions. Conditions are expected to gradually improve tomorrow. A broad surface high pressure over the north-central Atlantic will continue to promote moderate to locally fresh easterly winds across the regional waters during the next few days, keeping choppy to occasionally rough seas.

BEACH FORECAST

Issued at 335 AM AST Thu Nov 13 2025

An approaching north-northwesterly swell will spread across the local Atlantic Waters and Caribbean Passages today, deteriorating the coastal conditions into tonight. Thus, life-threatening rip currents are expected to form from Rincon to Fajardo and Culebra late tonight or early Thursday morning, creating a High Risk of rip currents. Meanwhile, the risk will moderate for the north- facing beaches along St. Thomas, St. John, and the Adjacent Islands. Conditions will improve gradually tomorrow.

SJU WATCHES/WARNINGS/ADVISORIES

PR...High Rip Current Risk through late tonight for PRZ001-002-005- 008-010.

High Surf Advisory until 6 PM AST this evening for PRZ001-002- 005-008-010.

High Rip Current Risk through late tonight for PRZ012.

VI...High Rip Current Risk through late tonight for VIZ001.

AM...Small Craft Advisory until 6 AM AST Friday for AMZ711.

Small Craft Advisory until 6 AM AST Friday for AMZ712-741-742.