Although Labor Day may seem to mark the unofficial end of summer, residents of several Western states will face a heat wave this week with temperatures in the triple digits.

The National Weather Service has issued an extreme heat warning for Southern California, the southern tip of Nevada and western Arizona.

Temperatures are expected to continue to rise throughout the week, reaching as high as 48 degrees Celsius in desert cities like Palm Springs.

The heatwave will peak on Thursday and Friday, mainly due to weak offshore winds and a heat dome, meteorologists said.

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In Phoenix, temperatures will range between 42 and 46 degrees Celsius every day this week.

According to Scripps News Phoenix, the record for days over 109 degrees was set last year with 55 days. They expect the record to be broken this week as there have already been 54 days over 109 degrees.

Since Tuesday, Phoenix has had 100 consecutive days of 38.8 degrees, breaking the previous record of 76 consecutive days of triple-digit temperatures set in August 1993.

According to Scripps News Las Vegas, high temperatures in Las Vegas will reach 41 degrees every day this week and only drop to just over 27 degrees at night.

Meanwhile, temperatures in Southern California will be 5 to 15 degrees above average this week. Scripps News San Diego said temperatures in the interior and mountains could reach as high as 42 degrees, while highs of 42 to 46 degrees are expected in desert regions.

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Temperatures in Southern California will only drop slightly this weekend, but additional monsoon moisture will bring more humidity, Scripps News San Diego reported.

The scorching start to September is no relief for residents, as many cities have already experienced the hottest meteorological summer on record, which ended in August.

According to Scripps News Phoenix, the average temperature in Phoenix this summer was 98.9 degrees, beating last year’s record of 97 degrees.

In Las Vegas, the average summer temperature was 34.4 degrees, with a high of 41.6 degrees. Scripps News Las Vegas reported that in addition to the highest daily high temperature ever – 49 degrees on July 7 – three other days in July also had record high temperatures.

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For the first time in history, Sin City experienced seven consecutive days of temperatures of 115 degrees Fahrenheit or more, and 11 consecutive days of temperatures of 110 degrees Fahrenheit or more, Scripps News Las Vegas reported.

The Centers for Disease Control and Prevention offers the following tips for protection in extreme heat:

• If possible, stay in air-conditioned indoor spaces.
• Drink plenty of fluids, even if you are not thirsty.
• Plan outdoor activities carefully.
• Wear loose, light and light-colored clothing and sunscreen.
• Take cool showers or baths to cool down.
• Stop by a friend or neighbor and ask someone to do the same for you.
• Never leave children or pets in the car.