Intense heat will continue affecting Puerto Rico on Thursday, November 12, with high temperatures and a heat index that could exceed 100 degrees Fahrenheit, while the National Weather Service (NWS) anticipates a slight increase in shower activity. Hot, humid conditions will persist, particularly in coastal and lower-elevation areas. On Wednesday, November 11, heat indices generally ranged between 100 and 107 degrees, though some stations recorded values above 107.
The heat of the past two days was also reflected in San Juan temperature records, with records broken on both Tuesday and Wednesday. According to the NWS forecast, on Thursday a trough system in the middle and upper levels of the atmosphere will slightly weaken a high-pressure zone that has favored mostly stable conditions, allowing a slight increase in humidity and shower frequency.
Some passing showers are expected in the morning, mainly in areas exposed to east winds, while isolated rainfall could develop in the afternoon from daytime heating, sea breezes and local terrain effects. Limited humidity and atmospheric stability will keep rain localized, so no widespread rainfall is anticipated. The NWS said a Heat Advisory could be issued if forecast heat indices and their duration meet established criteria, and it will continue evaluating conditions in upcoming forecasts.
For Friday, a high-pressure system is expected to strengthen again at middle levels, favoring mostly stable conditions and limiting shower development, with rain concentrated in isolated sectors during the afternoon. A moderate risk of dangerous rip currents will persist at most exposed beaches in Puerto Rico and the U.S. Virgin Islands. The NWS warned these currents can pose a danger to life and recommended swimming near lifeguards and respecting warnings posted at beaches.