San Diegans will not see relief from unusually high temperatures Thursday as an excessive heat warning for the inland valleys, mountains and deserts has been extended until Friday night.
The warning includes the communities of Escondido, El Cajon, San Marcos, La Mesa, Santee, and Poway, according to the National Weather Service.
Temperatures were expected to be 90 to 95 in the western valleys with temperatures from 95 to 102 in the inland valleys.
Residents in communities like Ramona will experience temperatures hovering at or above triple digits.
Wednesday saw only one record high with Campo at 108 degrees. Ramona tied a record with a 101-degree high.
Most of Arizona and parts of California, Nevada, and Utah have been under an extreme heat warning this week.
Michel Boudrias, a professor of Environmental and Ocean Sciences at the University of San Diego, told NBC 7 our region will likely see more heatwaves like the one we experienced this week.
"The data seems to indicate in the next 20 to 40 years we may have as many as six to eight times as many heatwave days as we've had in the last 20 to 30 years," Boudrias said.
He added more heatwaves will affect more than wildfire risk but also rain patterns and the public health.
Las Vegas authorities have said the city could see the hottest weather this year, while fire officials warned that conditions could be dangerous.
Temperatures were also scorching across the border in parts of northwestern Mexico.
In the border city of Mexicali, across from California, officials said some local pelicans were suffering heat stroke -- appearing weak, disoriented and dangerously dehydrated -- after the mercury spiked as high as 118.
Temperatures in Phoenix, Arizona hit 116 degrees on Wednesday, setting a new high for the date.
The Salt River Project utility that delivers electricity to about 2 million customers in Phoenix and the rest of central Arizona said demand was so great between 5 p.m. and 6 p.m. on Tuesday that it set a record of 7,252 megawatts to retail customers.
California ISO, the agency that manages the state's electric grid, said the forecasted peak of energy expected Thursday was 49,938 megawatts. The system's available capacity is 49,727 megawatts.
Flex Alerts were in effect Tuesday and Wednesday but as of 8 a.m. Thursday, no Flex Alert was in effect for California residents.
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