Millions and millions of Americans are being warned of "dangerous" heat in more than a dozen states as the summer 2025 season officially kicks off.
In parts of the Midwest and Mid-Atlantic regions more than 42 million were under extreme heat watches the morning of June 20, according to the National Weather Service. More than 37 million Americans were under heat advisories across much of the central part of the United States. Over 20 million are under extreme heat warnings.
The weather service says an extreme heat watch means residents should be prepared because conditions are favorable for an extreme heat event sometime soon. Those under a heat advisory or extreme heat warning should take action, according to the weather service. A heat advisory means there are dangerous heat conditions, while an extreme heat warning means extremely dangerous heat conditions are expected or already ongoing. You should avoid outdoor activities, drink plenty of water, take breaks in the shade and stay inside in air conditioning as much as possible.
High temperatures on June 20 are expected to range from triple digits in parts of Kansas, Nebraska and North Dakota to the low to mid-90s in the southeast and the high 80s in the Midwest and Mid-Atlantic. In some parts of the upper Midwest and Northern and Central Plains, record high minimum temperatures could be reached overnight, the weather service said.
