The National Weather Service San Juan office issued a heat advisory for all of Puerto Rico active from 9:00 AM to 5:00 PM on Oct 27, with the heat index expected to reach 100 F or higher.

The advisory came alongside a broader warning. NWS San Juan said on Oct 27 that unstable weather, including heat, rain, flooding and dangerous ocean conditions, would affect Puerto Rico. The office said the dangerous coastal conditions reach both Puerto Rico and the US Virgin Islands. The marine warnings extend an earlier set issued Oct 25 for Atlantic waters, the Mona Passage and Puerto Rico beaches.

Rain is wanted in specific places. Ernesto Rodríguez, San Juan director of the Servicio Nacional de Meteorología, said rain must fall in western zones of Cayey, Cidra, Aibonito, Comerío, Barranquitas, Naranjito and Toa Alta to refill La Plata reservoir.

The forecast puts two demands on the same day: a heat index at or above 100 F inland and dangerous surf on the coast. Whether the rain lands where Rodríguez says it is needed is the open question for La Plata.