Area Forecast Discussion
Issued by NWS San Juan, PR
Issued by NWS San Juan, PR
796 FXCA62 TJSJ 071842 AFDSJU Area Forecast Discussion National Weather Service San Juan PR 242 PM AST Sun Dec 7 2025 ...New SHORT TERM, LONG TERM, AVIATION, MARINE, BEACH FORECAST... .KEY MESSAGES... Issued at 200 PM AST Sun Dec 7 2025 * Fair weather conditions are expected through the first part of the workweek. However, showers embedded in the trades will move during the nighttime over portions of the islands, and particularly from midweek onward. * Winds will increase late in the week, leading to breezy to windy conditions across coastal and elevated areas by Thursday and Friday. Lightweight outdoor items may be blown around in exposed locations. * For the U.S. Virgin Islands, quick passing showers are expected during the night and early morning hours. Sunny to partly cloudy during the day. Winds will become noticeably stronger late in the week. * Marine and beach conditions will deteriorate during the second part of the workweek as increasing winds and an incoming long- period northerly swell raise seas and rip current risks. Hazardous surf and Small Craft Advisories are likely. && .Short Term(This evening through Tuesday)... Issued at 200 PM AST Sun Dec 7 2025 Sunny to partly cloudy skies prevailed across Puerto Rico and the U.S. Virgin Islands through the day. Scattered showers were noted early in the morning hours, mostly across the local waters and over portions of southeastern PR. Maximum temperatures were from the mid to upper 80s across the lower elevations of the islands, and from the upper 70s to low 80s across the higher elevations of Puerto Rico. The wind was from the east between 10 and 15 mph with sea breeze variations and higher gusts at times. For the rest of the short-term period, a strong mid-to upper- level ridge building northeast of the local area will continue to promote overall fair weather conditions. The precipitable water content is forecast to drop well below normal levels, and range between 1.00-1.35 inches. The best moisture content will remain trapped below 850mb. Winds will shift from the east to southeast as the surface high pressure over the central Atlantic shifts further east over the Azores. This will bring patches of moisture embedded in the trades at times, but particularly during the nighttime. Therefore, passing showers with limited rainfall accumulations are expected over the USVI and across the eastern portions of PR during this period. Across western PR, locally induced afternoon showers are expected each day, with minor flooding concerns. Also, sunny skies and southeasterly winds will promote normal to warmer than normal daytime temperatures across the islands on Monday and Tuesday. && .Long Term(Wednesday through next Saturday)... Issued at 449 AM AST Sun Dec 7 2025 A persistent and increasingly dominant mid-level ridge will govern the period, maintaining well-below-normal mid-level moisture. Recent model cycles show 700-500 mb relative humidity frequently dipping below 20 percent and at times near 10 percent, supporting a strong and persistent inversion based near 850 mb through most of the forecast period. This pattern will continue to favor stable conditions and suppress deep convection for the most part. However, occasional shallow moisture surges embedded in the trade winds will periodically lift the inversion height above the 700 mb layer, allowing for an uptick in passing showers. These events will favor the overnight and morning hours across windward coastal areas. During the afternoons, isolated to scattered showers remain possible across the interior and western Puerto Rico, but any thunderstorms that develop will be short-lived and very isolated. No significant flooding threat is expected. Toward the latter part of the period, surface high pressure over the central Atlantic is forecast to strengthen while a frontal boundary approaches from the northwest. This will tighten the pressure gradient across the northeastern Caribbean and result in breezy to windy conditions, especially across coastal and elevated areas from late week into the weekend. These winds may cause unsecured or lightweight outdoor items to blow around and could produce localized minor impacts in areas exposed to stronger gusts. Overall, conditions will remain largely stable with shallow convection, limited rainfall amounts, and a notable increase in winds late in the workweek into the weekend. && .AVIATION... (18Z TAFS) Issued at 200 PM AST Sun Dec 7 2025 Mainly VFR conditions are expected to prevail across all terminals during the next 24 hours. Brief iso -SHRA could move overnight across the USVI and eastern PR terminals. The 07/12z TJSJ sounding indicated ESE winds up to 22 kt blo FL050. && .MARINE... Issued at 200 PM AST Sun Dec 7 2025 Light to moderate east to southeasterly trades are expected to prevail through early in the workweek. By midweek, strengthening high pressure north of the region will tighten the pressure gradient and increase easterly winds, allowing seas to build across the Atlantic waters and exposed passages. At the same time, a long- period northerly swell arriving during the second part of the week will further worsen conditions. Hazardous seas building between 6 and 8 feet are expected Thursday into Friday, with Small Craft Advisories likely. A gradual improvement remains possible over the weekend as winds and swell ease. && .BEACH FORECAST... Issued at 200 PM AST Sun Dec 7 2025 A moderate risk of rip currents risk will persist through midweek along the northern beaches of the islands. On Thursday, a long period northerly swell will build seas up to 8 feet across the Atlantic waters and portions of the local passages through early in the weekend. This swell will cause large breaking waves along the Atlantic coastline of the islands, promoting rough surf conditions and life-threatening rip currents. && .SJU WATCHES/WARNINGS/ADVISORIES... PR...None. VI...None. AM...None. && $$ SHORT TERM...DSR LONG TERM....CVB AVIATION...DSR BEACH/MARINE...DSR