A major heat wave is spreading across much of the central and northeastern U.S. Tens of millions of Americans will be affected over the following week.

It is important to “beat the heat.” The Center for Disease Control and Prevent reported that nearly 0.5 percent of all emergency visits in New Mexico, Texas, Oklahoma, Arkansas and Louisiana last week were heat related. The average daily temperature in many of these places was in the upper 80s and low 90s.

To stay safe and out of the emergency room, know the signs of heat exhaustion and heat stroke.

Signs of heat exhaustion are dizziness, thirst, heavy sweating, nausea and weakness. Don’t wait to act, try to find a cooler location, sip cool water and loosen clothes to allow air to wick away sweat to cool you down.

If a person doesn’t cool-off quickly, heat stroke could occur. Signs of this dangerous condition are confusion, dizziness and becoming unconscious. If this occurs, seek immediate medical attention by calling 911.

Before help arrives, move the person to a cooler location, loosen clothes and remove extra layers and cool the body with water and ice.

To stay cool, always drink plenty of water and non-alcoholic and decaffeinated beverages. Wear loose-fitting clothing and plan outdoor activities for early morning hours when temperatures are coolest.

Remember to always check on elderly friends, family and neighbors. Senior citizens on fixed income might not be able to afford air conditioners or electric bills, so make sure to check on them and seek out social service assistance to get the air conditioning they need. Remember, older people are often affected well before everyone else and heat stroke could develop quickly.

Track all of the changes using our TemperatureRadar and get the latest heat related news in our Weather News section.