Phoenix may take a run at one of longest stretches of 90-degree heat in April

It was a blistering start to spring in the Southwest when record heat kicked off the first weekend in April. AccuWeather meteorologists say unseasonable heat, while not constantly toppling daily records across the region, persisted throughout much of this week. This pattern shows no signs of letting up early into the upcoming week which may have some residents in the southwestern United States wondering if the calendar flipped to May as opposed to April.

April temperatures so far have already been extreme. Phoenix's average temperature has been about 9.9 degrees Fahrenheit above normal so far this month, and Las Vegas has averaged 8.4 degrees above normal. The first weekend of April ushered record heat into the Southwest, helping to throttle temperatures so far above normal.

The jet stream will stay well to the north across the Pacific Northwest through early week, allowing unseasonably warm weather to prevail across a large portion of the Southwestern states.

"Even though records are not expected to be set, it is the early and persistent nature of the heat that is so unusual," AccuWeather Senior Meteorologist Brett Anderson said.

As a broad area of persistent high pressure sets up over northern Texas, afternoon high temperatures will soar 6-12 degrees Fahrenheit above normal for early April in cities like Phoenix, Flagstaff, Tucson and Yuma, Arizona, and Palm Springs and Needles, California, through early week.

Normal high temperatures range from 84 F in Phoenix to 77 F in Las Vegas and 83 F in Palm Springs, California, this time of year. Flagstaff, Arizona, typically has high temperatures around 57 degrees, and the normal high in Downtown Los Angeles is 72 F.

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While daily record highs are not likely in contention, one major city could take a run at the longest stretch of 90-degree weather.

Sky Harbor International Airport in Phoenix recorded ten consecutive days at or above 90-degree high temperatures through April 10. With unseasonably high temperatures set to continue into early week, Phoenix is on the road to reach a top-five streak of 90-degree days in April. The city may rack up a string of 12 days in a row where high temperatures of 90 or higher are reached through Monday, according to AccuWeather forecasters.

However, the stretch of hot weather is likely to be a far cry from the 23-day streak of 90-degree heat felt in Phoenix during April 1989, according to the National Weather Service. A stretch of 12 consecutive days at 90 or above would place this April in a tie for 4th place, behind the 15 days of 90-degree readings in April of 1946. Records have been kept at the location since 1896.

As unseasonably warm weather takes hold outside, temperatures inside vehicles will rapidly rise to lethal levels.

When the outside temperature is around 80 degrees, the inside of cars can rise up to 114 degrees in just 30 minutes -- and higher temperatures outdoors can lead to an even more rapid and extreme increases in temperature inside vehicles, according to the Phoenix National Weather Service. Cracking windows does little to slow the temperature rise. Officials and forecasters urge people never to leave children or pets unattended in vehicles, even for a few minutes.

Just one county over from Phoenix, a 150-acre wildfire broke out in Dudleyville, Arizona, in Pinal County, early on Thursday morning. The town was still in GO status as of early Saturday morning as the fire continued to move south, The Arizona State Forestry said. As of Sunday afternoon, the GO status for the area has been lifted in favor of SET mode.

Twelve structures were destroyed from the fire, which is being referred to as the Margo Fire. The cause of fire is unknown, but local salt cedar, grass, and brush continue to fuel it, according to InciWeb.

By 6 p.m., local time Thursday, the fire was about 20% contained across the 150 acres. As of late Friday night, the fire had spread to 1,200 acres and was 50% contained. By Sunday afternoon, containment had jumped to 61%.

Thick, dark smoke rises from the Margo Fire that was burning an estimated 150 acres in Dudleyville, Arizona, on Thursday, April 8, 2021, According to the Arizona State Forestry. (Arizona State Forestry)

As temperatures soar, conditions will also remain dry across the parched Southwestern states. Much of the region has been in the grips of an ongoing and extreme drought, with conditions ranging from severe to exceptional, according to the U.S. Drought Monitor. Exceptional is the highest category on the drought monitor's scale.

"With below-average precipitation statewide, California's reservoirs continue to show the impacts due to dry conditions," Sean De Guzman, Chief of Snow Surveys for the California Department of Water Resources, said. Most of the Golden State's reservoirs were filled to only half capacity as of April 1.

This image, captured on Thursday, April 8, 2021, shows a lack of clouds capable of producing precipitation over the southwestern United States. (CIRA at Colorado State/GOES-West)

This year's water season is tied for the third driest on record with the 2014 season, which has members of the AccuWeather long-range forecasting team very concerned about the upcoming fire season.

"Long-term severe drought will persist across the Four Corners region, despite going through a late-winter and early-spring surge of precipitation," AccuWeather Lead Long-Range Meteorologist Paul Pastelok said.

Significant rain isn't likely to arrive across California through this week, and just a little precipitation may arrive the week after that, according to AccuWeather Senior Meteorologist Dave Samuhel. The state is "running out of time" for chances of significant rainfall, he added.

The next good chance of rain across southern and central portions of California may not be until the middle or latter part of the North American Monsoon Season, which begins on June 15 and ends on Sept. 30, according to Pastelok.

"Much of the Southwest will deal with water shortages and wildfires through midsummer," Pastelok said, "and dryness can produce periods of very hot conditions throughout the early and middle part of the summer season."

By Tuesday and Wednesday, AccuWeather meteorologists expect the jet stream to shift southward into California, which could force the heat farther east and allow cooler, Pacific air to expand inland. Temperatures are expected to trend back toward normal mid-April levels as a result.

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