The US National Weather Service (NWS) announced on 28/6 that dangerous, record-high temperatures would spread across two-thirds of the US, concentrated in the central and eastern regions.

In areas including Ohio, parts of North Carolina, and Washington D.C., high temperatures and humidity will pose a particular danger to individuals with respiratory issues and the elderly.

According to the NWS, with high humidity, temperatures could reach 38-43 degrees C. Most of the central and eastern US faces a moderate to severe heat risk, potentially impacting the health of those who do not stay hydrated or cool, the NWS noted.

People use US flag images to shield themselves from the sun before the fair's opening at the National Mall in Washington D.C. on 24/6. *Photo: AFP*

Some areas of Iowa, Missouri, and Kansas are also under extreme heat alerts. A heat dome is causing this heatwave. This phenomenon occurs when a mass of very hot air remains stationary over an area, with a "lid" above the Earth's surface trapping it.

However, high temperatures are not the only concern, according to NWS meteorologist Bryan Putnam.

"Actual temperatures ranging from 32 to almost 40 degrees C are clearly very hot. However, when combined with high humidity, the heat index will sharply rise above 40 degrees C, and this is the temperature the body truly feels," Putnam stated.

The US National Weather Service (NWS) warned that the risk of extreme heat on the West Coast would continue after July 4th. During the day, the heat index could reach 38-40 degrees C, while nights would remain oppressive.

Computer model forecasts show a heat dome forming over the eastern US this week. *Photo: CNN Weather*

Putnam advised caution for those gathering outdoors during the July 4th weekend, including watching fireworks at night.

On 28/6, the Missouri State Emergency Management Agency recommended that residents "proactively plan and minimize prolonged outdoor exposure." The agency also emphasized the need for "immediate first aid" if anyone shows signs of heatstroke or heat exhaustion.

According to the US Centers for Disease Control and Prevention (CDC), common heat-related illnesses include exhaustion, rash, and heatstroke. Affected individuals may experience symptoms such as nausea, headache, confusion, or dizziness.

By Hoang Lan (According to NPR, AFP)