President Obama Warns Americans About the Weather

President Barack Obama warned Americans about an incoming heat wave this weekend, with at least 15 states already under heat advisories as a high-pressure system moves across the U.S. and spikes temperatures up to 110 degrees.

"This map says it all," Obama tweeted. "Stay safe as it heats up: Drink water, stay out of the sun, and check on your neighbors."

The map shows the maximum heat index for July 23 projected by the National Oceanic and Atmospheric Administration. The heat wave is expected to affect regions spanning California to Florida, and about half of the country could see temperatures exceeding 100 degrees over the weekend, with the highest temperatures hitting the Midwest and much of the South.

The U.S. is already experiencing exceptionally high temperatures, which has led climate scientists to project 2016 "will be the hottest year on record," Time reports. Experts believe that climate change is partly to blame for the upward trend.

The president's warning serves as an important reminder about the health risks of heat waves, particularly for the young and elderly.

Exposure to extreme heat can override the body's ability to cool itself, which sometimes leads to heat stroke. Centers for Disease Control and Prevention reports an average of 658 heat-related deaths in the U.S. each year, and the rate is only expected to rise.

heat-related deaths

"As global temperatures inexorably rise, scientists expect that average temperatures in North America will rise by another four degrees Fahrenheit — 11 degrees Fahrenheit this century," a 2012 report from the Natural Resources Defense Council warns. "As the number of dangerously hot days and heat waves increases, people — especially heat-vulnerable children and the elderly — will face higher risk for more deadly and dangerous health outcomes."

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