"The same high pressure area that brought record-challenging heat to the eastern two-thirds of the nation from late June through the Fourth of July will gradually re-position itself over the Southwest by week’s end and into the upcoming weekend," said AccuWeather Meteorologist Kyle Elliott.

Temperatures at the peak of the heat will run 10 to 20 degrees Fahrenheit above normal. This results in temperatures at or above 100 F in Los Angeles and near 90 F in San Diego.

A few desert locations could reach 120 F on one or both days.

High temperatures will challenge records from Los Angeles to San Diego as well as in Las Vegas and Phoenix.

The last stretch of 100-degree days in Los Angeles occurred from Oct. 23-25, 2017, with Oct. 24 being the hottest day at 104 F.

Typical dry air across the region will cause AccuWeather RealFeel® Temperatures to be at or just lower than the actual air temperature. Regardless, it will still feel uncomfortable for those going outside for extended periods of time.

Those hoping for relief from the heat at the California beaches will also contend with the hot weather.

"Even at the beaches, the lack of a morning marine layer, commonly referred to as 'June gloom,' will allow temperatures to range from the 80s to near or just above 90 on one or both days," Elliott said.

"The way the atmosphere is set up, there can be potent Sundowner winds in this pattern," according to AccuWeather Senior Meteorologist Ken Clark.

These winds tend to flow from north to south from Santa Barbara County to Los Angeles County in the mountains and through the north-south passes. The winds ramp up in the evening and last into the nighttime hours as the air cools over the higher elevations and descends to lower elevations, hence the name Sundowner winds. As the air descends, it heats up dramatically.

"It is very unusual to have this setup during July, especially to this magnitude," Clark said. "There is an enhanced risk for wildfire ignition and rapid spread considering the projected strength of the winds and heightened outdoor activity into this weekend."

Farther north, the worst of the heat will bypass much of the northern California coastline, including San Francisco.

"Residents planning prolonged outdoor activities this weekend should be sure to stay hydrated, take frequent breaks from the heat and make sure to never leave children or pets unattended in a closed vehicle," Elliott said.

The hot weather will make it difficult for firefighters to battle the ongoing blazes across the region, including the Lions Fire in the Sierra Nevada of California.

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Those hoping to take part in extended holiday celebrations will want to be sure to take the necessary precautions to protect against new fires and abide by any firework bans.

People will need to be very careful with outdoor flames and power equipment. Do not park vehicles over brush. Sparks and the hot exhaust system are enough to set off a blaze.

“Use extreme caution when dealing with grills, campfires, cigarette butts and any other activity that involves sparks or very hot surfaces,” AccuWeather Senior Meteorologist Kristina Pydynowski said.

This heat could begin to trigger scattered thunderstorm activity across the Four Corner states by the weekend, which can bring additional relief to firefighting efforts. However, any lightning strike could spark a new fire.

This stretch of hot weather will be short lived as slightly cooler and more seasonable weather returns next week.

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