A man and woman walk around Echo Park Lake on June 28, 2013.
UPDATE 4:02 p.m.: Dr. Eric Handler, Orange County's public health officer, says in the past few days, the O.C. has actually seen somewhat cooler temperatures than its neighbors to the north. But it still warrants caution, he said.
"There are people that are vulnerable to even high temperatures that we're currently seeing in Orange County," he said. "So when you're facing increased temperatures, you have to make sure that you drink plenty of water and you wear very light, loose fitting clothing and you limit your exposure to the sun and activity."
Even if it doesn't feel like Death Valley's soaring temperatures, folks still have to watch out for symptoms of heat exhaustion or heat stroke.
"Things like heavy sweating or muscle cramps, weakness or headaches, even nausea or vomiting are signs that you need to take care," Handler explained.
Something Southern California probably doesn't have to worry about is power. Steven Greenlee, a spokesman for California ISO – which monitors the state's electricity grid – said in the southern part of the state, the power supply is "tight but manageable," and will likely stay that way.
"The risk in that is, for instance, wildfires," he said. "And that's always a concern for us going forward. Also, we've now been running some of our generators pretty hard since the heat wave began, so generation breakdown is also a concern."
Previously: A heat wave baking much of the West may have tied a more than century-old record for the U.S. while putting Las Vegas through its hottest June on record.
The National Weather Service says California's Death Valley National Park tentatively recorded a high temperature of 129 degrees on Sunday, which would tie the all-time June record high for the United States. It could take months to verify whether the record set in 1902 at Volcano, a former town near the Salton Sea in southeastern California, was matched.
Las Vegas temperatures have been at 115 and above in recent days — including a record-tying 117 on Sunday — helping make June the hottest ever in Sin City.
Since record-keeping began in Las Vegas in 1937, the only other times the temperature reached 117 degrees were on July 19, 2005, and July 24, 1942, according to the National Weather Service.
Death Valley's record high of 134 degrees set nearly a century ago on July 10, 1913, stands as the planet's highest recorded temperature.
Las Vegas will continue to bake in near-record temperatures at least through Thursday, says National Weather Service meteorologist Chris Stachelski.
Meanwhile, Southern California will continue to broil, though forecasters say more record-setting temperatures are unlikely.
The National Weather Service says excessive-heat warnings remain in effect Monday for mountain and desert areas and for the Santa Clarita Valley.
NWS Meteorologist Rich Thompson says the San Fernando and San Gabriel valleys will see temperatures well into the 90s and approaching 100.
High-temperature records were shattered across the region over the weekend. The high of 115 at Lancaster's Fox Field on Sunday represented not just a record for a June 30 but an all-time high — surpassing the 114 degrees recorded 53 years ago.
In San Diego County, Campo set a record with a 107-degree mark.
A slight cooling is expected on Wednesday.
Tragedy struck north of Phoenix as hot gusty winds fueled an out of control wild fire that overtook and killed 19 firefighters near the town of Yarnell.
Forestry spokesman Art Morrison said the firefighters were forced to deploy their fire shelters, tent-like structures meant to shield firefighters from flames and heat.
Six half-marathon runners in Southern California were hospitalized Sunday for heat-related illnesses. A day earlier, paramedics responding to a Nevada home without air conditioning found an elderly man dead.
Runners in the Southern California race who required medical attention were extremely dehydrated, and some experienced cramps, Pasadena Fire Department spokeswoman Lisa Derderian said. Several other runners were evaluated along the route but weren't taken to the hospital, she said.
Paramedics were deployed along the 13.1-mile race, and buses with air conditioning were provided for runners to cool off. The event was supposed to be a marathon, but it was downgraded due to low turnout last year.
Hikers, bikers and dog walkers were scarce on typically busy trails in the Santa Monica Mountains above Los Angeles. At midday, two women and a panting German shepherd huddled in a rare sliver of shade along a fire road before striking out in the hot sun.
Atop San Vicente Peak, cyclist Jeff Disbrow, 49, of Santa Monica was clad in black and lathered in sweat as he took a break and refilled his water bottle.
"It's not the best day to be out here — unless you want to suffer," he said. "It's like Arizona."
In Utah, a record 105-degree heat caused an interstate on-ramp to buckle in Salt Lake City, and hampered firefighters in their battle against three wildfires. The Interstate 215 on-ramp had to be closed for four hours Saturday night after a short section of it expanded, Utah Department of Transportation spokesman John Gleason said.
The section looked like a pothole before it was repaved, he said. No problems were reported, and traffic was rerouted around the closed lane.
Phoenix Fire Department spokesman Larry Nunez said the city hasn't seen any deaths that were classified as heat-related, but emergency workers have gotten 98 heat-related calls within the metro area since Friday morning.
The 119-degree high in Phoenix on Saturday marked the fourth-hottest day in metro Phoenix since authorities started keeping temperature records more than 110 years ago. The high temperature for the metro area hit 115 on Sunday.
Temperatures could drop slightly in Phoenix within the coming days as monsoon storms are expected to make their way through the state. Such storms could bring cloud cover but could produce more humidity and possibly contribute to dust storms.
Several Southern California communities set same-day record highs Saturday including Palm Springs, where the mercury peaked at 122 degrees. In Northern California, Redding reported a high of 110, Sacramento had 107 while Fresno saw 109.
This story has been updated.