AFDSJU Area Forecast Discussion National Weather Service San Juan PR 856 AM AST Tue Mar 31 2026 ...New UPDATE... .UPDATE... Issued at 845 AM AST Tue Mar 31 2026 We update marine to include a Small Craft Advisory for the Surrounding waters of Vieques, Culebra, St Thomas and St John and the coastal hazards to start earlier the High Surf Advisory along the north- facing beaches of Vieques, Culebra, and the northern US Virgin Islands. && .KEY MESSAGES... Issued at 845 AM AST Tue Mar 31 2026 * Hazardous beach conditions will continue across Puerto Rico and the U.S. Virgin Islands. Life-threatening rip currents and dangerous surf are expected along north- and east-facing beaches. * Passing showers overnight and in the morning, with afternoon showers and isolated thunderstorms over western to southwestern Puerto Rico. Localized flooding is possible; lower risk across the U.S. Virgin Islands. * Isolated thunderstorms may develop, mainly in the afternoon, producing lightning, brief heavy rain, and gusty winds. * Breezy to locally windy conditions will persist, especially in coastal and exposed areas, supporting fast-moving showers. * These conditions may affect outdoor and holiday activities. Plan accordingly and stay weather-aware. && .Short Term(Today through Wednesday)... Issued at 200 AM AST Mon Mar 30 2026 Overnight, an increase in trade wind showers was observed moving inland from the Atlantic waters, with some reaching interior portions of Puerto Rico due to strong steering winds. These showers produced isolated rainfall amounts between 0.25 and 0.50 inches. Overnight low temperatures dropped into the mid 50s across higher elevations and mid 60s across lower elevations, reflecting slightly cooler-than-normal conditions that are expected to continue over the next few days. Breezy to locally windy northeasterly winds will persist across Puerto Rico and the U.S. Virgin Islands, driven by a strong surface high pressure over the western Atlantic. This pattern will continue to support frequent passing showers, especially during the overnight and early morning hours across windward areas. Aloft, a jet stream and a weak shortwave trough north of the region may help support slightly deeper moisture and limited instability starting Tuesday. Moisture will vary from time to time, with periods of drier and wetter air moving across the region. By Tuesday, a patch of higher moisture, possibly linked to remnants of a frontal boundary to the north, will move across the area, allowing for more active shower development. Afternoon heating will help showers grow over land, especially across interior and western Puerto Rico, following a typical pattern of morning showers in windward areas and afternoon activity inland. The main hazards will be localized flooding and breezy to windy conditions. While showers will move quickly, recent rainfall may have left soils sensitive, increasing the risk of ponding of water and minor flooding in urban areas, roads, and small streams. This risk will be higher in areas that receive frequent trade wind showers or repeated afternoon activity, particularly across interior and west to southwestern Puerto Rico. In addition, breezy to locally strong winds may result in occasional non-thunderstorm wind impacts, especially across exposed coastal areas and higher elevations. Lightning risk will remain limited, although a few thunderstorms are possible, mainly on Tuesday. Overall, impacts are expected to be localized rather than widespread. && .Long Term(Thursday through Monday)... Issued at 200 AM AST Mon Mar 30 2026 An induced surface trough northeast of the region along with a high pressure system well north of the region will maintain a breezy flow from the northeast, around 15 knots on Thursday. Passing showers will continue to move along the Virgin Islands and eastern Puerto Rico in the morning, followed by afternoon convection along the interior and western Puerto Rico. As the trough moves just north of the region, the winds will shift from the southeast by Friday and the weekend. Aloft, a short wave trough arrives on Friday, which usually will be favorable for strong thunderstorm development. However, it looks like that upper level clouds will move from the southwest as well. If the day stays cloudy, then it will shut down the diurnal heating mechanism, preventing heavy rain from developing. Since this is an evolving scenario, the confidence is low to medium at this time. Similar conditions will prevail on Saturday, with the influence of the upper level trough and high clouds moving from the southwest. By Sunday and Monday, there could 153be breaks in the cloud layer, which should allow for more warming and thunderstorms in the afternoon for western Puerto Rico. For these days, the risk of flooding will be elevated, with urban and small stream flooding likely. By the end of the period, temperatures are expected to warm up too, so highs could climb to the low 90s for most coastal areas in Puerto Rico and the Virgin Islands. && .AVIATION... (06Z TAFS) Issued at 845 AM AST Tue Mar 31 2026 SHRA will affect most terminals exposed to the north and across the islands with MVFR conds (cigs 23 kft, vsby 35 SM) and brief IFR (cigs <2 kft, vsby 3 SM) possible. TJPS less impacted early but SHRA/VCTS expected aft 31/17Z, with brief MVFR/IFR conds. SHRA will redevelop ovr windward terminals aft 31/22Z. NE winds 1015 kt overnight, incr to 1520 kt with gusts 2530 kt aft sunrise, then decreasing slightly overnight but remaining gusty, esp near SHRA/TSRA. Brief operational impacts likely due to reduced cigs/vsby and gusty winds. && .MARINE... Issued at 845 AM AST Tue Mar 31 2026 A broad and strong high pressure system over the western Atlantic will maintain a tight pressure gradient across the region, supporting moderate to locally strong northeasterly winds. A long- period northerly swell will spread across the regional waters today, with additional pulses expected over the next few days. The combination of these winds and building swell will result in hazardous marine conditions, with choppy to rough seas across the local waters and Small Craft Advisories in effect. Periods of frequent showers, and possibly isolated thunderstorms, will also move across the waters, locally reducing visibility and producing brief higher winds and rougher seas. Overall, hazardous marine conditions are expected to persist through much of the week. && .BEACH FORECAST... Issued at 845 AM AST Tue Mar 31 2026 A high risk of rip currents is now in effect for Vieques. Additionally, a High Surf Advisory is in effect for the north- facing beaches in Culebra, Vieques, St Thomas, St John, and Adjacent Islands. && .BEACH FORECAST... Issued at 845 AM AST Tue Mar 31 2026 A high risk of rip currents is in effect this morning along all north- and east-facing beaches of Puerto Rico, including Culebra, as well as the northern U.S. Virgin Islands. This risk will expand to Vieques and other exposed areas tonight as the swell continues to spread across the region. A low to moderate risk will persist along the remaining beaches, where rip currents are still possible. A High Surf Advisory is in effect for these same beaches, with conditions expected to expand to Culebra and the northern U.S. Virgin Islands tonight. Dangerous surf will create life- threatening rip currents and hazardous shoreline conditions, including strong breaking waves and wave run-up that can sweep people off rocks or the shoreline. Hazardous beach conditions are expected to persist through most, if not all, of the week and into the weekend. Beachgoers are urged to stay out of the water and use caution near the shoreline at affected beaches, as conditions can be dangerous even for those not entering the water. && .SJU WATCHES/WARNINGS/ADVISORIES... PR...High Rip Current Risk through Friday evening for PRZ001-002-005- 008-010-012. High Surf Advisory until 6 PM AST Wednesday for PRZ001-002-005- 008-010-012-013. High Rip Current Risk through late Wednesday night for PRZ013. VI...High Rip Current Risk through Friday evening for VIZ001. High Surf Advisory until 6 PM AST Wednesday for VIZ001. AM...Small Craft Advisory until midnight AST Friday night for AMZ711- 712-716-723-741-742. Small Craft Advisory until 6 AM AST Thursday for AMZ726. && $$