A tropical wave will increase rain in Puerto Rico during the afternoon and night, according to the National Meteorological Service (SNM). The typical September weather pattern will prevail during the day, with intense heat in coastal and urban areas, and isolated showers and thunderstorms in the interior and west. The SNM warned that the heat threat will continue in the coming days, with heat indices between limited and elevated, especially in coastal municipalities and highly urbanized areas. Although there will be passing rains in the east of Puerto Rico and the Virgin Islands during the morning, these will leave minimal accumulations and will not significantly alleviate the high temperatures.
As the day progresses, the combination of available humidity and diurnal heating will favor the development of isolated showers and thunderstorms in municipalities in the interior and west of the island. The atmospheric humidity content will remain near normal values for the time, with precipitable water between 1.9 and 2.0 inches. The areas with the highest probability of rain include the Central Cordillera and municipalities in the west, where moderate-intensity showers may occur during the afternoon. The most important change will begin from the end of the afternoon on Wednesday, when a weak tropical wave crosses the eastern Caribbean.
According to the forecast, rainfall activity will increase gradually during the night of Wednesday and will reach its most active point between the early morning and morning of Thursday. Periods of intense rain, isolated thunderstorms, and the possibility of urban and small stream flooding are expected in areas where showers persist.