The East Coast is in a dangerous heat wave. Will Phoenix see higher temps, too?
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Diverging Reports Breakdown
The East Coast is in a dangerous heat wave. Will Phoenix see higher temps, too?
A high-pressure system is trapping hot air from the Southwest in the eastern U.S. A low–pressure system has settled over the West, causing slightly lower temperatures in Arizona. Forecasters expect the subtropical ridge to shift back into the Southwest, which will raise temperatures and shift the wind pattern, bringing monsoonal moisture into the Valley. But that could soon change, with monsoon showers possible as early as July 4. The National Weather Service in Phoenix is predicting 110-degree-plus temperatures this weekend, raising the chance of monsoon activity in the region. The forecast shows temperatures returning to normal by Thursday. The East Coast will cool as the system moves. The West will remain hotter than the East, with highs in the 90s and lows in the 80s, forecasters say. The Southwest is expected to remain warmer than the West for the next few days.
Phoenix reached 117 degrees earlier in June, but temperatures are nearer to normal this week.
The forecast shows 110-degree-plus temperatures returning to Phoenix on the weekend, raising the chance of monsoon activity as early as July 4.
Phoenix is no stranger to triple-digit heat, but as eastern cities like Newark and Baltimore sizzled past 100 degrees and the Atlantic Coast melted under extreme heat warnings through June 25, temperatures in America’s hottest big city were hovering a little below normal.
In a twist of meteorological fortunes, it’s the desert that’s getting a breather from the heat while the Northeast and Midwest experience record-breaking temperatures.
A high-pressure system is trapping hot air from the Southwest in the eastern United States, with areas from Kansas to Maine reaching into the high 90s or even 100 degrees. A low–pressure system has settled over the West, causing slightly lower temperatures in Arizona.
High humidity makes the heat feel more intense in the East, with the heat index — how hot it feels with humidity — reaching up to 110 degrees in some areas.
Phoenix, which reached a season-high 117 degrees on June 19, will continue to see slightly lower-than-normal temperatures until returning to the 110s by June 29. The East Coast will cool as the system moves.
“As this system starts to move more eastward, the subtropical ridge does look to start building by early July, and will help bring our temperatures back up and hopefully move into a monsoon pattern,” said Alicia Ryan, a meteorologist with the National Weather Service in Phoenix.
Why is it so hot in the East?
On June 24, almost 33 million people across the eastern half of the country faced temperatures near or over 100 degrees, with heat indices up to 110 degrees.
Extreme heat warnings stretched from St. Louis to Boston.
Cities like New York, Washington D.C., Philadelphia, Pittsburgh, Chicago and Detroit all issued heat alerts. Philadelphia declared a heat emergency, while New York declared a state of emergency, activating emergency response plans in 32 counties.
Power grids were pushed to the limit as demand soared and Americans dropped their thermostats, with outages reported in several states.
Highs in the 90s and lows that barely dip below the 80s will shatter records in some areas in this rare heat wave.
Why Phoenix is cooler than normal, for now
But why is Phoenix cooler than normal in this atmospheric role reversal? It has to do with a major shift in upper-level weather patterns across the country.
“There’s a big trough-ridge system spanning across the entire mainland United States,” Ryan said. “We’re under a troughing low-pressure system, and that’s helping cool us off, and the eastern U.S. is under that giant ridge, which we’re normally under.”
The low-pressure system has helped suppress the temperatures in Phoenix, a rare occurrence in late June. But Phoenix residents shouldn’t get too comfortable.
“By Thursday, we’ll be near normal and then steadily climbing,” Ryan said.
When will it get hot in Arizona?
Phoenix should reach the 110s by June 29 and will hover around that mark for several days.
And while southeastern Arizona, particularly around Tucson, might see some chances for rain, Phoenix isn’t likely to catch any monsoon showers just yet. But that could soon change.
Ryan said that around July 4, forecasters expect the subtropical ridge to shift back into the Southwest, which will raise temperatures and shift the wind pattern, bringing monsoonal moisture into the Valley.
“It looks like the pattern change will be as early as July,” Ryan said. “So hopefully we can start getting more of that moisture pumped into our region.”
For once, Phoenix is a cooler spot on the map — but not for long.