textproduct: San Juan

KEY MESSAGES

Issued at 212 PM AST Fri Dec 19 2025

* Mostly fair weather will persist for the rest of the day and into the upcoming weekend, with passing showers and slightly warmer maximum temperatures.

* In the U.S. Virgin Islands, mostly stable weather is expected, with partly cloudy skies and minimal shower activity.

* A wet and unstable weather pattern is forecast for the upcoming workweek, with a high chance of widespread showers and isolated thunderstorms. Residents and visitors are urged to stay tuned for further updates.

* Hazardous marine and coastal conditions are forecast from Sunday onwards, as a northerly swell moves into the local waters.

Short Term(This evening through Sunday)

Issued at 212 PM AST Fri Dec 19 2025

Mostly sunny skies prevailed across the islands today. Maximum temperatures were from the mid to upper 80s across the lower elevations. The wind was from the northeast between 10 and 20 mph with higher gusts at times. Low-level clouds were developing over the islands around noon, with little to no rainfall activity detected over land areas as of 2 PM AST.

An upper-level ridge extending from the central Caribbean will continue to provide stable condtions in general across the islands for the rest of the short term period. However, patches of moisture embedded in the moderate to fresh trade winds will bring at times quick passing showers with mostly minor rainfall accumulations across the windward areas of the islands during the night and early morning hours. Across west/southwest PR, shallow afternoon convection is possible each afternoon, however, rainfall amounts are not expected to cause flood concerns. Regardless, ponding of water in roads and other poor drainage areas is possible.

Minimum temperatures will range from the low 60s across the higher elevations of PR, to the upper 60s and low 70s across the lower elevations of the islands. Daytime highs will continue from the mid to upper 80s across the southern and western lower elevations of PR.

Long Term(Monday through next Thursday)

Issued at 500 AM AST Thu Dec 18 2025

Late in the weekend and into early next week, a weak mid- to upper-level ridge will prevail across the region, supporting generally stable atmospheric conditions. During this period, precipitable water (PWAT) values are expected to remain below to near seasonal climatological levels, ranging from 1.2 to 1.6 inches. At the surface, patches of low-level moisture will continue to move through the area, producing brief passing showers over windward sections of the islands. Rainfall accumulations should remain limited, although isolated afternoon showers may develop across western Puerto Rico. From midweek onward, the mid- level ridge will gradually weaken as a polar trough departing the eastern United States advances from the northwest. This pattern change will increase atmospheric instability, with 500 mb temperatures cooling to below-normal values between -7 and -10 degrees Celsius. A transition toward higher rain chances is anticipated, with moderate probabilities (50 to 60%) for scattered to numerous showers. At the surface, an associated frontal boundary is forecast to approach the region around Wednesday into Thursday (Christmas Eve and Christmas Day) and potentially move across the area. As the front nears, moisture will increase, with PWAT values rising to between 1.5 and 1.8 inches, within the seasonal to above-normal range. The combination of cooler temperatures aloft and increased moisture supports a more unsettled pattern during the holiday period, including scattered showers and isolated thunderstorms. Guidance, including the Galvez-Davison Index, suggests the potential for shallow convection with isolated thunderstorm development. Periods of locally heavy rainfall may occur, which could elevate the risk of localized flooding in flood-prone and poorly drained areas, including ponding on roadways. At this time, the extended forecast indicates a limited flood risk. Also, cooler temperatures are expected in the wake of the possible frontal passage.

AVIATION

(18Z TAFS) Issued at 212 PM AST Fri Dec 19 2025

Mainly VFR conditions are expected to prevail across all terminals during the next 24 hours. Brief passing -SHRA should cause mostly VCSH across the USVI terminals and TJSJ. The wind will prevail from the ENE btw 15-20 kt blo FL050.

MARINE

Issued at 212 PM AST Fri Dec 19 2025

A weak surface low northeast of the region and a surface high pressure building over the western Atlantic will promote moderate to locally fresh (15-20 kt) east to northeast winds during the next few days. These winds, combined with additional pulses of northerly swells, will promote hazardous seas for small craft, particularly across the Atlantic waters and local passages from Saturday evening through Sunday. Small Craft Advisories conditions are expected due to seas building up to 7 feet.

BEACH FORECAST

Issued at 212 PM AST Fri Dec 19 2025

Fading northerly swell will continue to cause life-threatening rip currents along the northern beaches of PR and Culebra through this evening. Another long period northerly swell and increasing wind-driven seas will cause rough surf conditions and life- threatening rip currents once again from late Saturday through at least Monday, across all east and north facing beaches of the islands. Please follow the guidance of lifeguards, beach patrol flags, and signs.

SJU WATCHES/WARNINGS/ADVISORIES

PR...High Rip Current Risk until 6 PM AST this evening for PRZ001-002- 005-008-012.

VI...None. AM...Small Craft Advisory from noon Saturday to noon AST Sunday for AMZ711.