Relentless heat will bake parts of the West over the long Fourth of July weekend after nearly a week of record-setting temperatures.
Four million people remained under heat alerts Thursday across interior portions of the Pacific Northwest and northern Rockies, where temperatures 10 to 20 degrees above average will mean lows in the 90s and highs in the 100s.
For cities like Spokane, Washington; Boise, Idaho; and Missoula, Montana, the high heat will stick around through Sunday, July Fourth, with little relief in sight.
The blistering temperatures have worsened existing wildfires in California this week and caused dozens of new ones to break out across the state. The Lava Fire in Northern California grew to nearly 20,000 acres and was just 19 percent contained, as of Thursday morning.
Farther north, Lytton, Canada, the town that broke the national record for the highest temperature in Canada over three consecutive days, was evacuated Wednesday because of an explosive wildfire.
The fires that ignited Wednesday across British Columbia spewed smoke thousands of feet into the air and produced thousands of lightning strikes, perhaps sparking additional fires. Just before the Lytton weather station was knocked offline, the temperature registered 98 degrees and winds were gusting to 40 mph.
As the heat wave persists in the West, a tropical storm is threatening the Southeast.
Tropical Storm Elsa formed Thursday morning, breaking the record set just last year for the earliest fifth-named storm of the season.
As of Thursday morning, Elsa was 680 miles east-southeast of the Windward Islands and had maximum sustained winds of 45 mph. The storm was moving west at 28 mph. It is expected to gradually strengthen over the next few days into a fast-moving storm.
Tropical storm warnings were in effect for Barbados, Martinique, St. Lucia, and St. Vincent and the Grenadines. The system is forecast to pass near or over portions of the Windward Islands or the southern Leeward Islands on Friday before moving into the eastern Caribbean Sea on Friday night. It is expected to move near the southern coast of the Dominican Republic and Haiti on Saturday and threaten eastern Cuba on Sunday.
The storm could be near Florida next week.
Elsewhere, the holiday weekend will bring rain across the Northeast and New England, where scattered showers and thunderstorms are expected on Friday, with highs in the 70s and 80s.
Storms also are expected in parts of the Southeast, with temperatures reaching the 80s and 90s. Both the Midwest and West will be dry with mostly sunny skies. While temperatures will be around average for the Midwest, parts of the interior West will continue to bake under triple digit temperatures.
Saturday will be similar to Friday across most regions, with wet conditions possible for the Northeast and Southeast and dry with hot temperatures across the Midwest and West.
On Sunday, the Fourth of July, the Northeast and New England will dry out while the Gulf Coast remains stormy. Temperatures will warm up in the Midwest while staying hot in the West.
On Monday, most of the country will be relatively dry with the exception of storms along the Gulf Coast. And parts of the West will remain very hot.