The first day of summer in San Diego will see blistering, "dangerously hot" temperatures as a heat wave continues to pass through the county.
The forecast for the upcoming week is looking just as hot as the record-breaking hottest weekend of the year so far that San Diegans just got through.
"Unfortunately...(Sunday) wasn't even the forecasted highest, hottest day for us. (Monday) is looking to be even hotter for most areas," NBC 7's Vanessa Herrera said.
The National Weather Service (NWS) says an excessive heat watch will be in effect for parts of San Diego County, including valleys, mountains and deserts, from Sunday morning through next Thursday evening.
Communities that will feel the heat the most include: El Cajon; Santee; La Mesa; Poway; Pine Valley; Julian; Escondido; San Marcos; Lake Arrowhead; Big Bear.
The hot temperatures will cause electricity supplies to tighten in southern California Monday.
The state agency that regulates the power supply says Southern California residents should implement "flex alert" procedures Monday.
The Independent System Operator called the alert for Monday from 10 a.m. to 9 p.m.
A flex alert calls for voluntary conservation measures, such as turning off unnecessary lights, postponing use of major appliances and keeping thermostats at 78 degrees and higher.
Monday, expect temperatures in the 80s to the 110 across the county. Residents along the coast will see mid to upper 80s, residents in the valleys will see low 100s, residents in the mountains will see temperatures in the upper 90s and the deserts could see highs of up to 119 degrees.
A heat advisory along the coast is in effect until 8 p.m. Monday and temperatures will likely be warmer than Sunday. An excessive heat warning for the rest of the county has been extended through Tuesday for the inland valley and until Wednesday for the mountains and deserts.
"We're looking at dangerously hot temperatures," Herrera said.
Sunday, Ramona reached 106 degrees Sunday, breaking the old record of 102 set in 2008; Chula recorded 92 degrees, breaking the record set in 1957 by 4 degrees; El Cajon smashed the 15-year record of 94 degrees by reaching 104 degrees and Escondido broke a record set in 1929 by reaching 103 degrees.
Sunday, residents saw temperatures in the 80s along the coast. Valleys saw low 100s, mountains in the breezy upper 90s and deserts saw highs near 116.
"We’ll likely see several records broken around the county on Sunday and Monday, especially inland," Bledsoe said.
By Tuesday, San Diegans may see some relief.
"The area of high pressure over the southeast will begin to break down Tuesday, but even then, we’ll stay warmer than normal all week," Bledsoe said.
The warm weather could cause heat-related illness, especially in those partaking in strenuous outdoor activity. If you plan on spending time outside, reschedule activities to early morning or evening and wear loose fitting clothing. Also, drink plenty of water.
For a list of Cool Zones in San Diego County where you can go to beat the heat, click here.