AFDSJU Area Forecast Discussion National Weather Service San Juan PR 241 PM AST Wed Dec 17 2025 ...New SHORT TERM, LONG TERM, MARINE, BEACH FORECAST... .KEY MESSAGES... Issued at 218 PM AST Wed Dec 17 2025 * Pulses of a northerly swell will bring dangerous marine and beach conditions through Thursday morning, including high surf, localized coastal flooding, and life-threatening rip currents across north-facing beaches of Puerto Rico and the U.S. Virgin Islands. After Thursday morning, hazardous seas and dangerous rip currents will continue into early next week, mainly due to persistent moderate to fresh winds. * Moderate to fresh non-thunderstorm winds may affect exposed and elevated areas of Puerto Rico and the U.S. Virgin Islands, creating locally windy conditions at times, especially along exposed coastlines. * Thunderstorm and heavier rainfall impacts are mainly expected today, with passing showers and isolated storms capable of producing brief heavy rain, lightning, gusty winds, and localized minor flooding. These risks decrease tonight, but may return next week as a stronger weather system approaches. && .Short Term(This evening through Friday)... Issued at 218 PM AST Wed Dec 17 2025 An above-normal moisture patch moved across the region, producing scattered to locally numerous showers with periods of moderate to locally heavy rainfall. Since midnight, rainfall totals peaked near one inch across portions of southeastern Puerto Rico, while amounts across the U.S. Virgin Islands generally remained below a quarter of an inch. Skies were mostly cloudy, with clouds and showers spreading westward into the interior and western Puerto Rico. Temperatures ranged from the lower 60s across higher elevations of Puerto Rico to near 90 degrees in isolated areas of western Puerto Rico and Saint Croix. Winds were generally easterly at 12 to 18 mph, with occasional gusts near showers and local sea breeze influences. Showers will continue through the rest of today, with a few isolated thunderstorms possible this afternoon. While widespread severe weather is not expected, some showers may produce frequent lightning, gusty winds, and brief heavy rainfall, leading to localized ponding of water and reduced visibility. Winds will gradually increase as high pressure builds over the North Atlantic, remaining light and variable inland and strongest across exposed coastal areas. As drier air moves in this evening, shower coverage will decrease and the threat for lightning and heavy rainfall will diminish. Overnight low temperatures will range from the upper 60s to lower 70s across coastal and urban areas, and the mid-60s across the interior and higher elevations. From Thursday through Friday, weather conditions will become more stable as a mid-level ridge expands over the region, limiting sustained shower and thunderstorm development. A brief increase in moisture is possible Thursday night, but overall moisture levels will remain near normal, with increasing mid-level drying late Friday into early Saturday. Shower activity will be mainly trade- wind driven, favoring overnight and early morning hours across windward areas, with only limited afternoon activity over interior and western Puerto Rico. Winds will strengthen from Thursday afternoon into Thursday night, becoming moderate to locally breezy, then easing on Friday. Rainfall impacts should remain minor and short-lived, with little to no risk of excessive rainfall, flooding, or thunderstorms through 10Z Saturday. && .Long Term(Saturday through next Tuesday)... Issued at 429 AM AST Wed Dec 17 2025 A mid-to-upper-level ridge will dominate local weather for the first half of the period, maintaining stable conditions aloft. During this time, precipitable water (PWAT) values will remain below the seasonal climatological values, ranging from 1.2 to 1.5 inches. At the surface, patches of low-level moisture will continue to drift into the area, bringing passing showers to windward sections of the islands. Rainfall accumulations will stay limited, though localized afternoon showers are possible across western Puerto Rico. Overall impacts are expected to remain minimal. Transitioning into the second half of the period and through Christmas Eve, a wetter pattern will evolve. The mid-level ridge will erode as a polar trough, exiting the eastern U.S. coast, approaches from the northwest. This will increase instability, with 500mb temperatures dropping to between -6 and -8C. At the surface, an associated frontal boundary is forecast to approach late Tuesday into Wednesday. During this period moisture will increase, with PWAT values reaching 1.5 to 1.75 inches. This combination of cooling aloft and increased moisture suggests an unsettled pattern for the Christmas holiday, potentially bringing isolated thunderstorms and locally heavy rainfall that could increase the risk of flooding in prone areas starting late Tuesday or Wednesday. && .MARINE... Issued at 218 PM AST Wed Dec 17 2025 Moderate to locally fresh east-southeast winds will continue across the local waters today. Combined with pulses of a northerly swell, these conditions will maintain hazardous marine conditions for small craft, especially across the Atlantic waters and Caribbean Passages. As a result, a Small Craft Advisory remains in effect through at least Thursday morning. Winds will then increase and shift to the east to east-northeast as a broad surface high builds over the North Atlantic, producing a moderate to fresh breeze that will maintain hazardous marine conditions through the weekend and into early next week. && .BEACH FORECAST... Issued at 218 PM AST Wed Dec 17 2025 Life-threatening beach conditions will continue due to repeated pulses of a northerly swell. High Surf and Coastal Flood Advisories remain in effect for north-facing beaches of Puerto Rico, where large breaking waves, life-threatening rip currents, and minor coastal flooding are possible, especially from Rincn to Fajardo and around high tide. Culebra and the northern U.S. Virgin Islands will also face a life-threatening rip current risk. Small Craft Advisories remain in effect across the Atlantic waters and Caribbean passages. The rip current risk will expand tonight to the southwest coast of Puerto Rico and Vieques. While the northerly swell decreases after Thursday morning, strengthening east to east-northeast winds will continue to support life-threatening rip currents through the weekend and into early next week. Beachgoers should stay out of the water at affected beaches. && .SJU WATCHES/WARNINGS/ADVISORIES... PR...High Rip Current Risk through late tonight for PRZ001-002-005- 008-010-012. Coastal Flood Advisory until 6 PM AST this evening for PRZ001- 002-005-008-010. High Surf Advisory until 6 AM AST Thursday for PRZ001-002-005- 008-010. High Rip Current Risk from 6 PM AST this evening through late tonight for PRZ011-013. VI...High Rip Current Risk through late tonight for VIZ001. AM...Small Craft Advisory until 6 AM AST Thursday for AMZ711-712-716- 723-726-741-742. && $$