A massive dome of high pressure is expanding across the western United States, setting the stage for potentially record-breaking heat from the Desert Southwest into parts of the Rockies and northern Plains as the country moves toward the opening days of August.
Certified meteorologist Jonathan Kegges, host of the YouTube channel JustWeather, said the core of the heat will shift west after spending time over the Plains, with Arizona, California, Nevada, Utah, Colorado, New Mexico, Idaho, and Montana all falling under the influence of the strengthening ridge.
At the same time, the weather pattern will look almost completely different east of the Rockies, where a dip in the jet stream could bring cooler conditions, heavy rain in parts of the Northeast and Southeast, and a noticeable break from the oppressive summer heat.
The Heat Dome Builds Across the West
Kegges said the large area of high pressure will consolidate and expand through the second half of the week, becoming particularly intense around the start of August.
The strongest heat should be focused across Arizona, Nevada, California, Utah, and surrounding states, where temperatures could climb high enough to challenge daily records even in places already accustomed to extreme summer conditions.
Kegges pointed out that breaking heat records in the Desert Southwest is not easy because normal summer temperatures are already so high.
Yet his forecast for Saturday, August 1, showed Las Vegas near 115 degrees and Phoenix potentially approaching 120.
Salt Lake City could reach around 105 degrees, which Kegges said would be record territory, while Great Falls, Montana, could climb to roughly 106.
Even San Diego could get in on the record heat, with a forecast around 88 degrees.
Those numbers are remarkable not simply because they are hot, but because they cover such a broad region. A heat dome becomes especially concerning when extreme temperatures are not confined to one city or valley but instead stretch across several states at once.
The Heat Persists Into Sunday
Kegges expects the same general pattern to continue into Sunday, August 2, with widespread triple-digit temperatures across much of the West.
The ridge should remain strong for several days before the jet stream begins pressing down on its northern edge around August 3 through August 5.
That change could weaken the heat dome and reduce its grip, although Kegges did not suggest the region would suddenly become cool.
Instead, the most extreme part of the event should gradually ease.
The contrast with the eastern United States may be especially noticeable.
While the West bakes, Kegges showed much lower temperatures farther east, including around 87 degrees in Nashville and approximately 81 in Roanoke.
He also expects humidity to become less oppressive in some eastern areas as the jet stream dips southward.
Kegges described it as something resembling an early “morsel of fall,” which may sound unusual at the end of July, but the comparison makes sense when much of the East has been dealing with persistent summer heat and humidity.
Rain Shifts Toward New England and the Deep South
The same jet-stream pattern helping to cool the East will also focus more active weather into two main areas.
Kegges is watching New England for a possible coastal system that could bring several inches of rain over the coming days.
That is potentially bad timing because parts of New Jersey and the New York City area have already dealt with significant flooding in recent weeks.
Additional heavy rain over wet ground and urban areas could quickly create more drainage and flash-flooding concerns.
Farther south, a stalled front is expected to turn the rain back on across Florida and parts of the Deep South.
Kegges said the heavier rainfall should focus especially along the Gulf side of Florida and near the Interstate 75 corridor, while Alabama, southern Georgia, Mississippi, and southern Louisiana could also see periods of heavy rain.
Florida remains in drought in some areas, so much of the rain will be useful.
Still, Kegges warned that localized ponding and pockets of flooding could develop if storms repeatedly move over the same places.
That is one of the odd features of this broader pattern: the areas receiving the most rain are not necessarily the places that need it most.
The Driest Areas Stay Dry as Wildfires Expand
While Florida and the Northeast could pick up several inches of rainfall, Kegges said the Desert Southwest and parts of the interior West are expected to see very little.
That is particularly concerning because wildfire activity has increased sharply in Oregon and other parts of the Pacific Northwest.
Kegges highlighted numerous active fires, especially across eastern Oregon, with thick smoke spreading into surrounding states.
The heaviest smoke was expected to create significant air-quality problems across Idaho, Montana, and southern Canada.
Some of that smoke is also being pulled into the jet stream and carried much farther east.
Kegges said a lighter haze may eventually reach parts of the Southeast and even Florida, depending on cloud cover and atmospheric conditions.
He stressed that this should not produce the same widespread air-quality impact that smoke from Canadian wildfires has caused in the Northeast and Mid-Atlantic in other events.
Instead, much of the smoke farther east should be more noticeable as a thin haze.
The combination of intense heat, limited rainfall, and active fires is the part of this forecast that deserves particular attention in the West. High pressure suppresses rain, raises temperatures, and can also create conditions that allow fires to become harder to control.
Kegges Pushes Back on Hurricane Misinformation
Kegges also spent part of the forecast addressing what he described as misleading coverage surrounding Hurricane Fausto in the Pacific.
He said some headlines gave the impression that the storm would directly strike the United States or the Lower 48, while the actual forecast showed a much more limited threat.
Fausto is expected to pass north of the Hawaiian Islands while weakening, according to Kegges.
He said Hawaii could still experience outer rain bands, scattered downpours, gusty winds, larger surf, and stronger rip currents, but he did not expect a direct landfall.
Kegges emphasized that forecast guidance had been consistently shifting the track farther north, reducing the risk of major impacts across the islands.
He specifically noted that Kauai remained within part of the forecast cone, but said trends continued to favor the storm passing farther away.
That distinction matters because tropical systems can still create dangerous ocean conditions even when the center stays offshore.
A storm does not need to make landfall to increase surf, rip currents, or coastal hazards.
Hawaii Could Still See Dangerous Waves
Kegges said wave heights near the center of Fausto had reached roughly 20 to 22 feet before the storm weakened.
Around Hawaii, waves of roughly 10 feet could affect some areas, particularly north of the Big Island, before gradually subsiding later in the week.
Another powerful Pacific storm, Hurricane Genevieve, was also discussed.
Kegges described Genevieve as the first Category 5 hurricane of the eastern Pacific season, though it had already weakened from that level by the time of his update.
The storm remained far from land and was not expected to approach Hawaii directly.
However, its distant swells could still travel toward the islands and contribute to elevated surf through the weekend, potentially producing waves of eight to 10 feet and occasionally around 12 feet.
Kegges repeatedly urged viewers not to confuse high surf generated by a distant hurricane with a hurricane actually moving toward the islands.
That is a useful distinction because dramatic weather graphics can easily make a distant system appear more threatening than it is.
A Sharp Weather Divide Develops Across the Country
The larger story in Kegges’ forecast is the sharp split taking shape across the United States.
The West is heading into an expanding heat dome with potential record temperatures, little meaningful rainfall, and worsening wildfire concerns.
The East, meanwhile, should see a cooler jet-stream pattern with periods of rain and lower temperatures in many areas.
Parts of New England and the Deep South could face too much rain, while the driest parts of the West remain largely shut out.
By early August, Kegges expects the western ridge to begin weakening as the jet stream presses farther south.
Until then, cities from Phoenix and Las Vegas to Salt Lake City and Great Falls could experience some of their hottest weather of the season.
The most important message is not simply that it will be hot in the Southwest—that is normal in summer—but that the heat could become strong enough and widespread enough to challenge records across several states at once.
At the same time, wildfire smoke, flooding concerns in the East, and dangerous Pacific surf add several other hazards to an already unusual national weather pattern.
Mark grew up in the heart of Texas, where tornadoes and extreme weather were a part of life. His early experiences sparked a fascination with emergency preparedness and homesteading. A father of three, Mark is dedicated to teaching families how to be self-sufficient, with a focus on food storage, DIY projects, and energy independence. His writing empowers everyday people to take small steps toward greater self-reliance without feeling overwhelmed.
