An end to a stubborn heat wave that has broiled the region for nearly a week is in sight, but don’t expect relief just yet — and San Diego Gas & Electric customers will still be vulnerable to potential power outages.

Although some 14,000 customers around SDG&E’s service territory lost power for hours at a time on Sunday, by Monday morning that number had fallen to fewer than 1,000.

But utility officials said there’s a good chance the persistent heat could lead to another round of unplanned outages.

“When our equipment doesn’t even have a chance to cool off in the evening hours, it just puts tremendous amount of stress” on the system, said SDG&E spokesperson Alex Welling. More than 10,000 customers lost power Sunday in areas around Spring Valley and Rancho San Diego after the company’s substation in Jamacha went down.

Temperatures on Monday will be hot again, but the high-pressure system that’s been the source of the heat will begin to weaken as a low-pressure trough starts to move in, according to forecasters.

“We’ve got to hang on until Wednesday,” said Casey Oswalt, a meteorologist at the National Weather Service in San Diego. “We are getting an area of low pressure moving in from the Gulf of Alaska into the Pacific Northwest,” and that will push out the high-pressure system that’s lingered for six days.

Temperatures are expected to drop today to about 5 to 10 degrees above normal from the coasts to the deserts.

By Wednesday, forecasters anticipate the temperatures to fall another 10 to 15 degrees and “we’ll continue to see below average temperatures into early next week,” Oswalt said.

In the meantime, though, an excessive heat warning is still in effect through 8 p.m. Monday.

Inland cities like Ramona, Escondido, El Cajon and Alpine were all expected to top 100 degrees again. Even usually balmy coastal areas were expected to swelter: Oceanside was forecast to top out at 90, San Diego at 89.

The heat wave that began Sept. 4 has made for an uncharacteristically swampy kind of heat across the region that has led to records being set in some communities for “high lows” — that is, when the lowest temperature overnight on any given day is still unusually hot.

On Sunday, the temperature in Escondido fell only to 79 degrees, breaking a record that had stood since 2015. The low temperature at San Diego International Airport came to a still-warm 75 degrees, tying the record set in 2022.

“It’s just not cooling off overnight, and that’s really what’s contributing to these really excessively hot conditions,” Oswalt said.

The extended heat wave has not yet prompted the California Independent System Operator, which manages the electric grid for about 80 percent of the state, to issue any requests for customers to voluntarily reduce their energy use.

But the grid operator has called on utilities and other entities that participate in energy markets around California to avoid conducting maintenance work so that all available generation and transmission lines stay in service. That directive remains in effect until 10 p.m. Monday.

When outages occur, “our crews are going to be working as hard as they possibly can in this heat to get your power back up as quickly and safely as possible,” SDG&E’s Welling said.