Phoenix smashes all-time hottest month record
A grueling stretch of 110-degree heat has blown away the old record. That level of heat will take a brief break, but another shift in the pattern will help temperatures notch up once again, AccuWeather meteorologists say.
Transportation officials in Arizona say a special treatment on residential streets to reduce heat absorption is paying off and this summer they hit a milestone.
July 2023 not only ended up being the hottest July on record, but it also shattered the hottest month ever recorded for Phoenix by about 4 degrees Fahrenheit, AccuWeather meteorologists say. The Arizona metropolis finished the month with an average temperature (combining high and low temperatures) of 102.7 degrees.
With 30 of 31 days of high temperatures at or above 110 F and a total of 19 nights where the temperature failed to drop below 90, it's no wonder that July 2023 will go down in the history books as an incredibly hot month for Phoenix.
The grueling 31-day stretch of consecutive days with high temperatures at or above 110-degrees Fahrenheit began on June 30 and is the longest-ever stretch since record-keeping began in 1895. The old record of 18 days in a row with 110 F plus heat, previously set in 1974, was blown away.
A jet takes flight from Sky Harbor International Airport as the sun sets over Phoenix, July 12, 2023. (AP Photo/Matt York, File)
Prior to 2023, the hottest July on record in Phoenix was set in 2020 with an average temperature of 98.9 degrees. That same summer also brought the hottest month on record, which was August. The average temperature for the aptly named "Valley of the Sun" was 99.1 in August 2020.
To beat the prior record by such a wide margin is phenomenal, according to meteorologists. Most often when a monthly temperature record is topped, it is done so by a few tenths of a degree.
High temperatures in Phoenix are forecast by AccuWeather meteorologists to be below 110 F through Wednesday thanks to an uptick in cloud cover, thunderstorm activity and higher humidity levels.
But even though high temperatures will remain below 110 through midweek, conditions will still be dangerously hot and should not be taken lightly. AccuWeather RealFeel® Temperatures will still be in the danger zone and near the 110-degree mark for several hours during the midday and afternoon due to the amount of sunshine and high humidity levels.
Earlier in July, the city set a warm night record where the temperature did not drop below the 90-degree mark for 16 straight nights. The record before this month was set in 2020 with 11 straight days with lows of 90 or higher. The overnight low of 97 on July 19 also shattered the mark for the highest low temperature ever recorded.
AccuWeather forecasters warn that 110-degree highs are expected to return soon as hot and dry conditions will build back later this week and beyond. And, on top of that, even with the monsoon pattern in place this week, only sporadic rainfall is anticipated in the Phoenix area.
Monsoon to continue sporadic storms, rainfall into Thursday
A phenomenon known as the North American monsoon will continue to bring high humidity levels and fairly widespread shower and thunderstorm activity through the middle of the week over the interior Southwest.
Contrary to what many people may believe, a monsoon is not defined by the rain it brings, but rather it is associated with the wind direction. In the case of the western United States, a more persistent southerly breeze sets up during monsoon season. It draws in humid air from the Gulf of Mexico, the Pacific Ocean, Mexico and Central America.
This year's monsoon has been very late to take the weather stage. In some years, the flip of the winds can bring an uptick in thunderstorm activity as early as June. AccuWeather's long-range team of meteorologists, headed by expert Paul Pastelok, has been anticipating a later and weaker monsoon for the summer of 2023 since soon after the start of the new year.
Into midweek, the presence of moisture and a disturbance will trigger thunderstorms capable of gusty winds that can kick up dust and create sudden low visibility, as well as sporadic heavy rainfall that can lead to localized flash floods, AccuWeather Meteorologist Haley Taylor said.
The flash flood threat will be most significant in but not limited to urban areas and recent wildfire burn scar locations. However, where little or no rainfall occurs, frequent lightning strikes can ignite brush that has been drying out in the hot summer sun.
During the latter part of this week, as humidity levels drop and a dome of high pressure expands westward from Texas, heat will rebound in the region, and the chances of storms will decrease.
Rain, storms to occur around Las Vegas
The same disturbance and higher humidity levels that will spark storms in Arizona into midweek will increase the potential for rain in parts of the Las Vegas area.
"Downpours that erupt around Las Vegas or any other location in Nevada, Arizona and interior Southern California will carry the potential of flash flooding," AccuWeather Senior Meteorologist Adam Douty said.
Prior to July 31, only one day brought measurable rain (0.01 of an inch or greater) in Las Vegas, Nevada, since March. On June 16, showers delivered 0.20 of an inch. Downpours delivered some rain to the city on Tuesday. The potential for thunderstorms and flash flooding exists around Las Vegas into Wednesday.
"Downtown Los Angeles is likely to remain free of rain, despite the disturbance and uptick in moisture," Douty said.
Hikers in the region should be aware of both the increased risk of lightning strikes over the ridges and the potential for flash floods in the valleys and canyons below, forecasters warn. A thunderstorm several miles away can trigger a flash flood downstream through a dry canyon or arroyo, even where the sky may be clear overhead.
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