Puerto Rico and the U.S. Virgin Islands are under a heat advisory from the National Weather Service on Thursday, Nov. 12. The advisory runs from 10 a.m. to 5 p.m. Atlantic Standard Time. Forecasters say the heat poses the greatest risk in coastal areas, lowlands, interior valleys and urban neighborhoods.

People who are sensitive to heat or lack reliable cooling are more likely to become ill. The weather service also warns that heat can worsen symptoms for people with chronic conditions. If you work outdoors or have plans that involve a lot of walking, schedule the hardest activity earlier in the morning or after the advisory ends, when possible. Take breaks in a cool place and drink water regularly.

Watch for signs of heat illness

The weather service’s heat safety guidance lists dizziness, nausea and heavy sweating as possible signs of heat exhaustion. Move to a cooler place and take steps to cool down. Confusion, fainting or loss of consciousness can signal heat stroke. Call 911 if you suspect heat stroke and begin cooling the person while help is on the way.

Check on relatives or neighbors who may have trouble cooling their homes during the afternoon. For any changes to the advisory or local forecast, use the National Weather Service’s San Juan office.