In Washington DC, park officials announced that the Washington Monument will close early at 13:00 local time as the storm drew closer.
“Beware of possible flash flooding, standing water, strong wind, lightning and hail,” the Park Police said in a statement on X.
A tornado watch was issued for the US capital.
Canadians were also facing severe weather on Monday, particularly in central Ontario and south-western Quebec. Forecasters in the region predicted up to 20in of snow with wind speeds up to 49mph, warning of “near zero visibility” in some areas.
On the US west coast, an extreme heat watch was scheduled to go into effect for parts of southern California, Arizona and Nevada later this week.
Temperatures in southwest Arizona were expected to reach up to 109F (42C). Officials there warned of a “significant increase” in the chance of heat related illness.
On Wednesday, Phoenix could have its earliest day of temperatures exceeding 100F in nearly four decades.
The high temperatures and dry, windy pattern was also expected to increase wildfire danger across parts of the West and High Plains.
Over the weekend in Nebraska, roughly 30 National Guard troops were deployed to combat multiple wildfires, the state’s emergency management agency said.
Nearly 1,000 sq miles (1,609 sq km) had already been damaged as of Saturday, the agency said. At least one fire-related fatality was reported.
A storm that soaked Hawaii over the weekend has shattered rainfall records dating to 1951, including nearly 24in of rain in Maui.
With its widespread impacts, forecasters say this could be one of the most significant weather events to hit the US so far this year, potentially affecting roughly 200 million people across multiple states.
