America's holiday weather: Hot as a firecracker in west, stormy July 4 expected in east

July 3 (UPI) -- Shade, shelter and lots of fluids will be needed to safely enjoy the Fourth of July celebrations on Tuesday as intense heat and storms are expected.

The National Oceanic and Atmospheric Administration forecasts "dangerously hot temperatures" along the West Coast, as well as some locations in the southeastern United States.

The West Coast was in the grips of excessive heat on Monday. The Los Angeles County Health Department has continued its excessive heat warning through Monday night at 8 p.m. in the Antelope and Santa Clarita valleys and parts of San Luis Obispo County. The mountainous regions of Los Angeles and Ventura and San Bernardino counties are also under extended warnings, KTLA reports.

Temperatures may yet reach record-breaking levels in the west with some locations in California having hit 105 degrees on Sunday.

The heat has been even more intense in southern Nevada, where temperatures reached an excess of 120 degrees on Monday. The National Weather Service Las Vegas headquarters tweeted that temperatures remained well above normal on Monday.

On Sunday, the agency said it tied the record of the shortest amount of time between its first 100-degree day and 110-degree day. The time between was two days, matching 1955 as the only other time this has happened.

To the south, Phoenix is set to reach above its average of 110-degree days in the coming week. The temperature has reached or surpassed 110 degrees six times this year. It is forecasted to be 110 degrees or more for at least the next seven days.

Monday's afternoon highs in Phoenix and the surrounding area were between 111 and 116 degrees. The area remains under an excessive heat warning through Tuesday. An ozone high pollution advisory is also in effect through Tuesday.

Record and severe heat is not isolated to the West Coast and southwest. Minnesota reported its hottest day of the year on Monday. The heat is ushering a swath of scattered thunderstorms for Minnesota and Wisconsin. Some thunderstorms in Wisconsin may be severe.

Heavy rain and thunderstorms are expected to disrupt holiday plans in the Southeast, Mid-Atlantic, Northeast, Great Plains and throughout the Rockies on Tuesday. There are chances of flash floods, hail and damaging winds for these areas.

The 43rd annual "A Capitol Fourth Concert" may be affected by storms and temperatures topping out in excess of 90 degrees. Artists, including Chicago, Babyface and Go-Go's singer Belinda Carlisle rehearsed on Monday in preparation for their Fourth of July performances.

The event is open to the public and there is no ticket required. The concert will be held at the West Lawn of the Capitol.

And in the city that gave birth to American independence, many of Philadelphia's weekend festivities were postponed or canceled due to severe weather. The inclement weather continued into Monday for southeastern Pennsylvania, as well as much of Maryland, Delaware and Virginia.

The National Weather Service for Mount Holly, which covers the Philadelphia area, upgraded a majority of its coverage area to an "enhanced risk" of severe thunderstorms.

Despite the storms, the combination of high heat and humidity remains a concern across the East Coast, with temperatures in the 90s on Tuesday.