AFDSJU Area Forecast Discussion National Weather Service San Juan PR 226 PM AST Fri Dec 26 2025 ...New SHORT TERM, LONG TERM, AVIATION, MARINE, BEACH FORECAST... .KEY MESSAGES... Issued at 215 PM AST Fri Dec 26 2025 * Choppy to rough seas and life-threatening rip currents are expected to continue for the rest of today into the weekend, becoming hazardous for small craft and beachgoers. Small Craft Advisories and High Rip Current Risk are in effect, with High Surf Advisory conditions likely. Residents and visitors are encouraged to heed the advice of the flag warning system and stay onshore. * Mostly fair conditions are anticipated for the next few days, with passing showers across northern and eastern portions of Puerto Rico and St. Thomas and St. John in the U.S. Virgin Islands during the night hours. * Cooler than normal temperatures could lead to patchy fog, particularly over interior portions of Puerto Rico, during the morning commute. && .Short Term(This evening through Sunday)... Issued at 215 PM AST Fri Dec 26 2025 A very stable weather pattern prevailed throughout the morning and into early afternoon, with mostly clear skies and a few clouds, especially across the northern section of Puerto Rico. Colder temperatures were observed during the morning hours, with lows in the 60s across the interior and in the lower 70s across areas. AS of 11 AM, daytime temperatures are rising to the mid-80s along the coast and slightly cooler across the mountains, according to unofficial weather stations around the islands. The U.S. Virgin Islands observed similar conditions, with daytime temperatures ranging from the low 70s to the low 80s. Similar weather conditions will persist for the rest of the day as a surface high-pressure system extending from the western Atlantic into the Caribbean continues to push dry, colder temperatures across the forecast area. According to the latest derived imagery from the GOES satellite, Precipitable water values around the islands range between 0.80 and 1.0 inches, which is well below climatological normals. Although conditions at the surface remained quite hostile to shower development, recent model comparison data indicate colder temperatures at 500 MB and lower 250 heights, suggesting an unstable weather pattern at the upper levels. Given the expected conditions, for tonight into Saturday, mostly stable weather will persist, with colder nights and minimal shower and cloud activity. On Saturday into Sunday, a surface change in winds due to an induced surface trough well to the east of the islands and an extending surface high pressure over the central Atlantic will aid weak easterly winds across the islands. Under this weather pattern, the islands will experience light to moderate winds with mostly stable conditions. On Saturday, both model guidance (GFS and ECMWF) show an increase in RH slightly above 50% between 700 and 850 MB. However, deep shower activity is not forecast due to extremely dry 500-700 MB values, which are two standard deviations below normal. && .Long Term(Monday through next Thursday)... Issued at 508 AM AST Fri Dec 26 2025 A shift in the weather pattern is expected this week. After a relatively dry start on Monday and Tuesday, wetter conditions return Tuesday night and persist through Friday as a weak frontal boundary dissipates and a short-wave polar trough approaches the region, with a surface trough reflection increasing moisture and instability later in the week. Showers will become more frequent, with periods of moderate to locally heavy rainfall, especially from Thursday afternoon into Friday. While widespread flooding is not expected, localized urban and small-stream flooding will be possible, mainly across windward and interior areas of Puerto Rico and portions of the U.S. Virgin Islands. Confidence is moderate that late-week rainfall will be the most impactful part of the period. Thunderstorm activity is expected to remain limited overall, which is typical for this time of year, but there is a low to moderate chance of thunderstorms Thursday into Friday as the trough briefly enhances instability and supports isolated thunderstorm development. Winds will remain a gentle east-southeast to southeast breeze through Thursday, then veer to the east and strengthen to a moderate breeze from Thursday night into Friday as surface high pressure builds and shifts eastward over the North Atlantic. Temperatures will trend slightly warmer from Wednesday through New Years, with cooler conditions expected to return late in the week. Confidence is high in the late-week increase in wind speeds, resulting in breezy conditions at times, especially along exposed coasts and higher elevations. && .AVIATION... (18Z TAFS) Issued at 215 PM AST Fri Dec 26 2025 VFR conditions are expected to prevail across all TAF sites through the forecast period. Surface winds will remain from the NNE at 1015 kt, with occasional gusts possible, particularly during daytime hours. For TJBQ, mostly clear skies (SKC to FEW) are expected for most of the period, with ceilings remaining above FL040FL050, posing no restrictions on VIS or CIG. VCSH may affect TISX, TIST, and TJSJ between 26/20Z and 27/12Z; however, brief MVFR conditions cannot be ruled out within passing showers. && .MARINE... Issued at 215 PM AST Fri Dec 26 2025 A surface high pressure centered over the western Atlantic and a frontal boundary north of the CWA will promote light to moderate east to northeast winds over the next few days. A long-period northerly swell will arrive tonight and spread across the local waters and Caribbean passages, resulting in choppy to rough seas and hazardous conditions for small craft. Hence, Small Craft Advisories are in effect for the Atlantic offshore and coastal waters and the Mona and Anegada Passages from tonight through late Saturday night. Additional pulses of northerly swell are expected early next week, which will likely once again bring hazardous conditions for small craft across the local waters. Seasonal trade- wind passing showers will occasionally move across the regional waters, particularly during nighttime hours. && .BEACH FORECAST... Issued at 215 PM AST Fri Dec 26 2025 No major changes were introduced to the beach forecast, with pulses of a northerly swell arriving this weekend and early next week that will deteriorate coastal conditions. NOAA NDBC 41043, located 170 NM NNE of San Juan, reported an increase in WV during the morning hours, the latest observation being 7.9 ft at 14 seconds. Based on the latest model guidance, the first pulse is expected to arrive tonight before midnight and spread across the local waters and Caribbean passages, increasing breaking wave heights and becoming hazardous for beachgoers. Hence, the rip current risk will remain high along north-facing beaches of Puerto Rico, including Culebra, and St. Thomas and St. John in the U.S. Virgin Islands through at least late Saturday night. Beachgoers are urged to avoid these beaches, as life-threatening rip currents will develop in the surf zone. As other pulses are expected to arrive later in the weekend, residents and visitors are encouraged to check the beach forecast before going out and heed the advice of the flag warning system. Stay tuned for the next updates, as large breaking waves are likely and a High Surf Advisory will be required. && .SJU WATCHES/WARNINGS/ADVISORIES... PR...High Rip Current Risk through late Saturday night for PRZ001-002- 005-008-010-012. VI...High Rip Current Risk from Saturday morning through late Saturday night for VIZ001. AM...Small Craft Advisory from 6 PM this evening to 6 PM AST Saturday for AMZ711. Small Craft Advisory from midnight tonight to 6 PM AST Saturday for AMZ712-716-723-741-742. && $$