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Cities in the U.S. Southwest are bracing for record-breaking high temperatures over the next few days, which may put the lives of some in jeopardy.
EXTREME HEAT | Southwestern U.S.

Safety a concern as searing heat grips Southwest U.S.

Monday, June 12, 2017, 5:56 - High temperatures have been the norm across much of the Southwest this Father's Day weekend but, daytime temperatures are expected to climb even higher midweek, threatening the all-time temperature records in various locations across the region.

Some areas of Arizona, Nevada and interior California are expected to see temperature values soaring into the 115 to 120oF mark. California already saw some daily records this weekend, but this week's heat event could mean record values for cities like Phoenix, which has an all-time record of 122oF set back in June 26, 1990. Las Vegas will not climb quite as high but is expected to reach the 110 to 115oF, not far from the all-time record of 117oF on June 30, 2013.

It is not unusual to run into this extreme heat in the southwest this time of year. It's a typical weather pattern which forms prior to the onset of the classical summer monsoon. The highest temperatures of the year normally come during the second half of June as shown in NOAA's "Warmest Day of the Year" map.

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Areas of southern Arizona, southern New Mexico and extreme southwest Texas experience the warmest temperatures these days. The heat then becomes less intense as moist air begins to flow from the Pacific and the Gulf of Mexico, and cooling thunderstorms begin to affect the region in the afternoon and evening hours.

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This week high pressure will continue to dominate much of the western US with heat trapped underneath this large dome and temperatures increasing further as the sinking air associated with the high continues to compress and warm. The heat will be especially dangerous during the middle of the week as it intensifies even more in some areas of California, Arizona and extreme southern Nevada. Nighttime temperatures are also expected to remain above normal with values in the 80s and 90s.


Temperatures along the coast will be warm but not as extreme as in the inland areas. Los Angeles is expected to reach highs in the mid 80s, but Palm Springs, Yuma or Death Valley, the warmest spot in the world, are expected to see values climb above 120oF. Even in the northern valleys of the state, cities like Sacramento are expected to see temperatures close 110oF.

Below: Heat outlook for Southern California


The largest populated urban areas affected by this heat event will be those in Arizona. Phoenix is forecast to see highs in the 118 to 119oF mark until at least Wednesday. Tucson will be slightly cooler with daytime highs around 115oF.

Below: Phoenix Forecast


Las Vegas will be another hot spot in the middle of the desert with highs around 115oF, further north Reno will enjoy a more contained heat episode with values close to 100oF.

Below: Reno Forecast


Despite the region being used to these exceptionally high temperature values, people in the region and those travelling to visit should be very careful with the extreme heat. Limit your outdoor exposure during the intense heat hours, wear light clothing and stay as hydrated as possible even when the sun is not shining to its full potential.

The Southwest is susceptible to extreme temperatures with highs commonly reaching over 110oF during the U.S. Monsoon season, which officially began on June 15. In addition, during this time of year, humidity levels reach high levels and lead to exceptionally warm evenings with low temperatures sometimes not dropping below 90 degrees.


At Phoenix Sky Harbor International Airport, American Airlines canceled 43 inbound and outbound flights during the peak-heat hours of 3 p.m. through 6 p.m. local time, after cancelling seven on Monday. Passengers may rebook their flights or get full refunds, American said. 

The airline said it does not expect to cancel any Phoenix flights on Wednesday, but will reevaluate early in the day. 

The canceled flights are part of the airline's regional flight system, and are operated by other carriers that use Bombardier aircraft which are not permitted to fly when temperatures exceed 118 degrees, American said. 

Smaller aircraft, such as those made by Bombardier, are more susceptible to heat, which makes air less dense and reduces lift, than larger, more powerful aircraft. Phoenix, which tied a record high temperature on Tuesday at 118 degrees, is no stranger to extreme heat. 

The all-time high temperature for Sky Harbor Airport was 122 degrees on June 26, 1990. 

In Death Valley in eastern California and in the town of Needles near the Arizona border, the National Weather Service is forecasting high temperatures of 127 degrees Fahrenheit this week. 

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The National Park Service cautioned tourists there about the "EXTREME SUMMER HEAT" in a warning on its website. It also issued an "Excessive Heat Warning" at the Grand Canyon in Arizona, urging hikers to hydrate themselves and eat salty snacks. 

Power grid operators and utility companies urged customers to conserve electricity at peak times to avoid the possibility of blackouts. 

The high pressure system stretched north to Alaska, where it was blamed for creating dry conditions that enabled lightning strikes to start forest fires.

With files from Reuters

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