SAN DIEGO — Officials warned of potentially dangerous heat in parts of San Diego County Sunday, with a stretch of early-summer scorchers to start the week.

The National Weather Service issued a heat advisory from 10 a.m. Sunday to 8 p.m. Monday for the region’s valleys, including parts of Escondido, El Cajon, San Marcos, La Mesa, Santee and Poway.

Temperatures will range from 95 to over 100 degrees, the weather service said. It will be cooler but still warm at the coast, with highs near 80 degrees in San Diego and Oceanside.

Forecasters expect hot conditions to last several days as high pressure builds over the western U.S. More seasonal conditions should return by late in the coming week, officials said.

Sunday’s advisory covered some other Southern California communities too, including the Santa Ana Mountains and foothills and inland areas of Orange County.

“Drink plenty of fluids, avoid the midday sun if possible, and check up on relatives and neighbors,” the advisory reads, in part. “Young children and pets should never be left unattended in vehicles under any circumstances.”

Forecasters also advised taking extra precautions if you must work outside, including rescheduling activities for early morning or the evening and wearing lightweight and loose-fitting clothing, when possible.

“Heat stroke is an emergency!” the advisory continues. You should call 911 and move the person to a cooler area, loosening their clothing and cooling them with water or ice.

Symptoms of heat stroke include confusion, dizziness and trouble keeping consciousness.

Heat exhaustion, which can lead to heat stroke, is more mild: Symptoms include thirst, heavy sweating, nausea and weakness. People should move somewhere cool, sip water and loosen their clothing, monitoring symptoms and getting medical attention if they don’t improve.