More than half the country is under some degree of heat advisory.

According to a warning issued by the National Weather Service, the United States is due for a severe heat wave over the weekend, with residents of over half of the country under heat advisories coast to coast. The majority of the country is slated to experience temperatures over 90 degrees Fahrenheit, while the central-southern United States are expected to exceed 100.

According to medical authorities, who are preparing to offer emergency services to address brush fires and heatstroke, this kind of heat doesn’t usually occur until later in the summer. “Those numbers are what we would expect to see in mid- to late-August,” Adam Paluka, spokesperson for the Emergency Medical Services Authority, said Wednesday. “So we’re four to six weeks ahead of where we would normally see those mid-200 call numbers.”

“It’s very concerning,” he added, “especially because the amount of patients that are being transported indicates that some of those calls are heatstroke, which can be deadly.”

Various states are advising their citizenry to stay inside as much as possible and avoid dangerous heat conditions such as strenuous outdoor activity. Texas authorities in particular have expressed concern that the heat could place a greater strain on their already-struggling power grid, and are asking residents to try and conserve power where they can.

As this local heat looms and another heat wave coats Europe and the UK on the other side of the world, climate experts are warning that these kinds of severe heat waves will become more common as global climate change worsens.