KEY POINTS

  • The potentially dangerous heatwave is expected over then next two weeks as temperatures are forecast to surpass 100 degrees fahrenheit in several states
  • High humidity is forecast for the Gulf Coast, causing a wave of severe storms and rainfall that may lead to flooding but isn't expected to break the heat
  • Strong winds are expected in Arizona, which could cause the multiple wildfires burning in the state to spread out-of-state

Parts of the central and southern U.S. prepared Thursday for a potentially dangerous combination of heat and humidity beginning for the Fourth of July weekend. The National Weather Service warned temperatures could exceed 100 degrees Fahrenheit in several areas.

“Max temperature departures will hover around 12 degrees above normal in these regions, which combined with dew points in the upper 70s could lead to heat indices approaching the century mark,” the National Weather Service said in its forecast. “Lastly, ensemble guidance is hinting at the development of a large upper ridge forming over the southern High Plains and Rockies towards the middle of next week. High temperatures could make a run at 100 degrees and heat indices over 100 degrees in the central Plains.”

The heat was expected to be exacerbated by humidity from the Gulf of Mexico, creating what meteorologists refer to as an “oppressive” heat along the Gulf Coast. It largely will be felt in Louisiana, Texas, Oklahoma, Arkansas and Kansas over the next two weeks. The National Weather Service said this will likely lead to scattered rainfall and storms across the area, along with the southeastern coastline, though it may not be enough to break the heat.

It also was unclear what areas could be in danger of flooding in the next two weeks.

“Where guidance becomes increasingly unclear is the positioning and movement of the trough, which makes areas at risk for heavy rainfall tricky,” the National Weather Service said. “The heaviest precipitation is currently forecast to extend from the Florida Panhandle to the South Carolina coast. There is still the potential for heavier rainfall elsewhere in the Southeast depending on the positioning and speed of the upper trough.”

While humidity looks to be the added factor for the Gulf Coast and southeastern U.S., high winds are expected to come alongside the heat in the Southwest.

Multiple wildfires were burning across Arizona, and the National Weather Service warned strong winds could carry embers to Colorado, Utah, New Mexico and western Texas.

“High winds in addition to the expected dry, hot weather may exacerbate or prolong ongoing drought conditions and increase wildfire risk across the Four Corners region and western Texas,” the National Weather Service warned.

Another concern is how deadly this latest heatwave could prove, especially with coronavirus surging in several states along the heatwave's path.

Texas, Arizona and Florida have been three of the biggest hotspots recently, with more new cases reported daily as the states have turned course on reopening. This has left several cooling centers closed over the risk of exposure and put many Americans in danger of suffering from heat-related illnesses or death.

"If you have limited resources, significant underlying health issues and live in a particularly warm spot in the city’s landscape or work in an outdoor job, that can prove to be a recipe for heat illness or even fatality," Science Museum of Virginia chief scientist Jeremy Hoffman told CNBC.

HeatWaveNewYork People cool off in a fountain during a heat wave called a "heat dome" in the Manhattan borough of New York, July 23, 2016. Photo: REUTERS/Eduardo Munoz