Extreme heat searing the Southwest this week

Dangerously hot temperatures are gripping the Southwest this week, potentially threatening the all-time record-high temperature in both Las Vegas and Phoenix.

A large dome of high pressure in the upper atmosphere has developed over the Southwest. Beneath the dome, sinking air is causing temperatures to soar well over 110 degrees in many areas.

See more on heat waves:

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Beating the heat in Bangkok
A chimpanzee drinks a sweet refreshment as it is sprayed with water on a hot day at Dusit zoo in Bangkok, Thailand, March 30, 2017. REUTERS/Chaiwat Subprasom TPX IMAGES OF THE DAY
A child plays in a pool during a hot day at Dusit zoo in Bangkok, Thailand, on March 30, 2017. (Photo by Anusak Laowilas/NurPhoto via Getty Images)
A chimpanzee drinks cold fruit juice given by a zoo keeper during a hot day at Dusit Zoo in Bangkok, Thailand, on March 30, 2017. (Photo by Anusak Laowilas/NurPhoto via Getty Images)
A mahout sits on an elephant as they play in a pool during a hot day at Dusit zoo in Bangkok, Thailand, on March 30, 2017. (Photo by Anusak Laowilas/NurPhoto via Getty Images)
A Malayan sun bear licks a block of ice during a hot day at Dusit zoo in Bangkok, Thailand, on March 30, 2017. (Photo by Anusak Laowilas/NurPhoto via Getty Images)
A monkey eats a frozen fruit during a hot day at Dusit Zoo in Bangkok, Thailand, on March 30, 2017. (Photo by Anusak Laowilas/NurPhoto via Getty Images)
A mahout sits on an elephant as they play in a pool during a hot day at Dusit zoo in Bangkok, Thailand, on March 30, 2017. (Photo by Anusak Laowilas/NurPhoto via Getty Images)
An Asian black bear sleeping a hot day at Dusit zoo in Bangkok, Thailand, on March 30, 2017. (Photo by Anusak Laowilas/NurPhoto via Getty Images)
A elephant eats a frozen fruit during a hot day at Dusit Zoo in Bangkok, Thailand, on March 30, 2017. (Photo by Anusak Laowilas/NurPhoto via Getty Images)
A Malayan sun bear licks a block of ice during a hot day at Dusit zoo in Bangkok, Thailand, March 30, 2017. REUTERS/Chaiwat Subprasom
A mahout sits on an elephant as they play in a pool during a hot day at Dusit zoo in Bangkok, Thailand, March 30, 2017. REUTERS/Chaiwat Subprasom
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This is a classic pre-monsoon heat event for the Southwest region. Some of the highest temperatures of the year can be recorded before the onset of the summer monsoon. Humidity levels are low, so the sun's energy can be used to heat the air rather than being absorbed by water vapor or used for evaporation.

(MORE: 5 Things to Expect During the Summer Monsoon)

Various heat alerts have been issued by the National Weather Service across Arizona, western New Mexico, southern Utah, southern Nevada and portions of California.

Several daily record highs were set Monday, including Phoenix (118 degrees), Tucson, Arizona (115 degrees), Palm Springs, California (119 degrees), and Reno, Nevada (103 degrees).

The 115-degree high in Tucson, Arizona, on Monday was the third hottest temperature ever recorded in that city and only the sixth time it has been 115 degrees or hotter since the late 1800s.

Dangerous Heat This Week

Here's what can be expected from this excessive heat event.

Arizona

Phoenix: Highs will reach or exceed 115 degrees through at least midweek. Daily record highs will be within reach (current standing record is shown): 116 degrees for Tuesday and 115 degrees for Wednesday. In fact, Phoenix could approach its all-time record high of 122 degrees (June 26, 1990) on Tuesday. It will also be within reach of tying the record for consecutive days of high temperatures greater than 115 degrees, which is 4 days set in 1990. Not much relief is expected overnight, as temperatures will only "cool off" into the upper 80s to near 90 degrees.

Tucson: Afternoon readings are forecast to max out near 115 degrees through midweek, which would threaten daily record highs. The high temperature in Tucson has only been 115 degrees or hotter six times since the late 1800s, including June 19, 2017 and June 19, 2016. The all-time record high in Tucson is 117 degrees (June 26, 1990).

(MORE: How Often Your City Reaches 100 Degrees)

California

Central Valley: Triple-digit heat will engulf Bakersfield, Fresno and Sacramento through this week. Highs will approach 110 degrees in several cities at times this week. Some daily record highs will be within striking distance.

Southern California: As is typical, the hottest temperatures will be in the deserts with highs 110 to 120 degrees. Areas just inland from the Southern California coast will also be hot, including Anaheim, Ontario and Fullerton.

Nevada

Las Vegas: Temperatures are forecast to be 110 degrees or hotter through this week, approaching or exceeding daily record highs at times. The all-time record high of 117 degrees could be threatened Tuesday through Thursday.

Reno: Highs in the upper 90s to near 100 degrees are possible through midweek, which would approach daily record highs.

The hot conditions this week will be particularly dangerous for vulnerable groups, such as the sick and the elderly. The NWS offered useful heat safety tips that can be incorporated into a daily routine when extreme heat sets in.

Job sites: Stay hydrated and take breaks inside as often as possible. Remember that in temperatures above 110, you will not know that you are sweating.

Indoors: Check up on the elderly, sick and those without air conditioning.

In vehicles: Never leave children or pets unattended – look before you lock.

Outdoors: Limit strenuous activities and find shade. Drink plenty of water and avoid alcohol.

Also, remember that flights planes may be delayed or canceled in temperatures of 115 or more due to the lost of lift that planes need to fly.

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