033 FXCA62 TJSJ 291713 AFDSJU Area Forecast Discussion National Weather Service San Juan PR 113 PM AST Mon Jun 29 2026 ...New SHORT TERM, LONG TERM, AVIATION, MARINE, BEACH FORECAST... .KEY MESSAGES... Issued at 108 PM AST Mon Jun 29 2026 * Shower and thunderstorm activity for the rest of today, resulting in ponding of water over roadways and poorly drained areas, including urban and small stream flooding, across the islands. * Warmer to hot conditions are expected for the next few days, with heat indices exceeding 100 degrees Fahrenheit across urban and low- lying areas of Puerto Rico and the U.S. Virgin Islands. Stay hydrated. * Moderate to high concentrations of Saharan Dust will filter into the region tonight into Tuesday, resulting in hazy skies, reduced visibility, and poor air quality. Sensitive groups must follow medical recommendations. && .Short Term(This evening through Wednesday)... Issued at 108 PM AST Mon Jun 29 2026 Today was generally calm across Puerto Rico and the U.S. Virgin Islands with a few passing showers that moved across the islands from time to time. Afternoon temperatures reached the upper 80s to mid 90s across coastal and urban areas, while higher elevations remained in the upper 70s to lower 80s. By the early afternoon, daytime heating, local effects, and exiting tropical wave allowed showers to become stronger and produce lightning across the north- central to northwestern sections of Puerto Rico. This activity is currently ongoing. Tonight, a much drier and more stable air mass will gradually spread across the region. At the same time, moderate to high concentrations of Saharan dust will gradually filter inland. On Tuesday, expect the highest concentrations of Saharan Dust. As a result, skies will become hazier, rainfall coverage will decrease, and shower activity will be limited mainly to brief, fast-moving trade wind showers. Sensitive groups, including individuals with respiratory conditions, are urged to limit prolonged outdoor exposure and take necessary precautions. Tuesday through Wednesday, a broad Atlantic high-pressure system and a strengthening mid-level ridge will maintain stable weather conditions across the northeastern Caribbean. While a few passing showers cannot be ruled out, especially during the overnight and morning hours, widespread or significant rainfall is not expected. The combination of increased sunshine and drier conditions will allow temperatures to rise into the 90s across coastal and urban areas, with heat index values reaching or exceeding 100°F during the afternoon. Residents and visitors are encouraged to stay hydrated, limit prolonged outdoor activities during the hottest part of the day, and take frequent breaks in shaded or air-conditioned areas. && .Long Term(Thursday through next Sunday)... Issued at 257 AM AST Mon Jun 29 2026 For the long-term forecast period, the region will experience a transition from a marginally unstable environment to a drier, hazier pattern before moisture returns early next week on Monday. At the surface, a dominant high-pressure system will maintain a generally easterly low-level wind flow, which is expected to veer to the southeast by Thursday morning. Aloft, a 250 mb cut-off low will linger near the local area from Thursday into Friday, providing modest upper-level support and atmospheric instability, with 500 mb temperatures forecast to hover between -8 °C and -7 °C during this time. On the other hand, precipitable water values are expected to range between 1.4 and 1.6 inches. Given the expected conditions, passing showers are anticipated across eastern sections of Puerto Rico during the morning hours, followed by the development of afternoon showers over the western interior and northwestern quadrants of the island, fueled by local effects and daytime heating. From Friday through Sunday, a slightly drier weather pattern will establish across the forecast area. Available moisture will become relatively shallow, generally trapped between the 1000 and 850 mb levels. Furthermore, recent NASA Goddard aerosol model guidance indicates the arrival of another mass of Saharan particulates. This dust will result in hazy skies, leading to mostly dry and variable conditions with very limited rainfall accumulations throughout the weekend. By Monday, a more uniform area of low-level moisture is forecast to filter into the region. This will aid in diminishing the hazy conditions as dust concentrations decrease, promoting a return to a more typical, scattered shower pattern across the islands. Regardless of the fluctuations in moisture and Saharan dust, persistently warm to hot conditions will dominate the entirety of the long-term period. An elevated heat threat is expected each day, particularly across urban and coastal areas. Maximum heat index values will consistently peak between 100 and 108 °F across portions of the north-central coastal plain and southern sectors of Puerto Rico during the peak daytime heating hours. && .AVIATION... (18Z TAFS) Issued at 108 PM AST Mon Jun 29 2026 VFR conds are expected to prevail across all TAF sites. However, a tropical wave will enhance the development of SHRA and iso TS over TJBQ & TJSJ throu 29/22Z. SE winds between 12-16 kt are expected with higher gusts near TS and sea breeze variations. Winds will become light and variable at 5-10 kt aft 29/23Z, increasing back to around 15kts by 30/12Z across more TAF sites. && .MARINE... Issued at 108 PM AST Mon Jun 29 2026 A tropical wave near the Mona Passage will continue to bring showers and isolated thunderstorms across the regional waters and Caribbean Passages, with gusty winds and lightning, creating localized hazardous conditions for small craft. Following the tropical wave, a dense Saharan Air Layer will filter into the region tonight through Wednesday, bringing hazy skies and reduced visibility. The surface high pressure across the Central Atlantic will promote the return of moderate to locally fresh east-to-east-southeasterly winds, resulting in choppy seas across regional waters. && .BEACH FORECAST... Issued at 108 PM AST Mon Jun 29 2026 No changes were introduced to the beach forecast, as the risk of rip currents should remain low across most beaches of Puerto Rico and the U.S. Virgin Islands for the next few days. Nevertheless, beachgoers should pay attention to the beach conditions, as life- threatening rip currents can often occur near groins, jetties, reefs, and piers. The risk should gradually increase by the upcoming weekend, as the local pressure gradient increases and winds strengthen, with a moderate risk of rip currents across most beaches of the islands. Besides rip currents, showers and isolated thunderstorms can be expected for the rest of today due to the influence of a tropical wave near the Dominican Republic, which could move near coastal areas of the islands. As the tropical wave continues to move across the Caribbean Basin, moderate to high concentrations of Saharan Dust will gradually filter into the region tonight, persisting through Wednesday. These concentrations will result in hazy skies, reduced visibility, and poor air quality. && .SJU WATCHES/WARNINGS/ADVISORIES... PR...None. VI...None. AM...None. && $$ SHORT TERM/AVIATION...MMC LONG TERM...LIS MARINE/BEACH FORECAST...MNG