Much of the United States is on alert for a dangerous heat wave

The US National Weather Service (NWS) said on June 28 that record-breaking dangerous temperatures would spread across two-thirds of the United States, concentrated in the central and eastern regions.

In areas including Ohio, parts of North Carolina and Washington DC, high temperatures and humidity will be especially dangerous for people with respiratory problems and the elderly.

According to NWS, with the combination of high humidity, heat could reach 38-43 degrees Celsius. Much of the central and eastern United States is under moderate to severe heat risk, which could cause health effects for people without additional water or cooling, NWS noted.

Parts of Iowa, Missouri and Kansas are also under extreme heat warnings. Heat domes are the cause of this heat wave. This is a phenomenon that occurs when a mass of very hot air stands still over an area and becomes trapped under a “lid” above the Earth’s surface.

But high temperatures aren’t the only concern, NWS forecaster Bryan Putnam said.

“The actual temperature ranges from 32 to nearly 40 degrees Celsius, which is obviously very hot. However, when combined with high humidity, the heat perception index will increase sharply to above 40 degrees Celsius, and this is the level of body heat actually felt,” Mr. Putnam said.

The US National Weather Service (NWS) warns that the risk of extreme heat on the West Coast will continue after Independence Day, July 4. During the day, the heat index can reach 38-40 degrees Celsius, while at night it is still sultry.

People gathering outdoors over the Fourth of July weekend, including watching fireworks at night, should be cautious, Putnam said.

On June 28, the Missouri State Emergency Management Agency advised people to “proactively plan and minimize being outdoors for long periods of time.” The agency also emphasized the need for “immediate first aid” if anyone is detected showing signs of heat stroke or heat exhaustion.

According to the US Centers for Disease Control and Prevention (CDC), common illnesses caused by heat include exhaustion, rash and heat stroke. Patients may experience symptoms such as nausea, headache, confusion or dizziness.