Move over, heat waves; there’s a new weather phenomenon in town. Meteorologists (with some generous help from the media) have dubbed 2016 the summer of the “heat dome,” a scary-sounding buzzword that’s set to affect much of the country this week.

A “heat dome,” according to the New York Times, is a “bubble of high pressure that sits in the mid- to upper atmosphere and pushes warm air down toward the ground.” In a tongue-in-cheek article about the connotations of the word “dome,” the Times writes, “A heat wave is just passing through. Wave hi! A dome sits there.”

That’s a joke, but there’s some truth to it. NBC News reports that heat domes tend last for prolonged periods of time. And because high temperatures are often associated with poor air quality—along with something known as “corn sweat” in the Midwest, in which water released from plant leaves leaves the air extra muggy—heat domes can indeed be uncomfortable, and even dangerous for some people.

With this current heat dome set to affect more than half of United States today and into this weekend, we though it might be a good time for a refresher course in what to do—and what not to do—during periods of extreme heat. Follow these tips to stay safe and beat the heat.

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Limit outdoor activity

When temperatures soar, try to avoid strenuous physical activity—like working out or doing manual labor—during the hottest times of the day when the sun is highest. If you must spend time outdoors, do so in the morning and the evening.

Hydrate early and often

Staying hydrated can help your body better adapt to high temperatures. (Cold water works best, as it cools down your internal organs.) It will also ensure that you are sweating effectively—nature’s way of cooling you down.

Keep an eye on sensitive groups

Older adults and anyone with a chronic illness is at higher risk for a heat-related illness, says Peter Shearer, MD, associate director of the Mount Sinai Hospital emergency department in New York City. Make sure loved ones in these groups have access to shade and cool air—preferably an air conditioned space—during these times.

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Don’t let kids judge for themselves

Young children are another sensitive group when it comes to heat susceptibility. “They can have so much fun running around outside that they don’t realize that they’re overheating,” says Dr. Shearer. “Parents need to encourage them to take breaks, stay hydrated, and come inside when it gets too hot.”

Keep your skin cool

When it’s really humid, sweat can’t evaporate from your skin—which means heat can’t leave your body as efficiently. You can help the process along by exposing your skin to moving air; even just fanning yourself with a hand-held fan can help, says Dr. Shearer. Spritzing water on your skin can also help mimic your body’s natural sweating process.

Watch for warning signs

If you’re outdoors in the heat and start to experience cramps or headaches, get yourself to cooler air right away. (These are often signs of heat exhaustion, which can lead to more dangerous heat stroke if not treated.) Dizziness, confusion, and a lack of sweating can also signal serious trouble. Here are more signs you’ve spent too much time in the heat, and how to respond if that does happen.