Excessive heat warnings issued for Maricopa, Pima counties

The National Weather Service in Phoenix has issued an excessive heat warning for Maricopa County starting at 12:14 a.m. July 7. The warning expires at 3 p.m. July 7. The National Weather Service in Tucson also issued an excessive heat warning for Pima County starting at 1:18 a.m. July 7. Pima's excessive warning expires at 8 p.m. on July 9.

For the latest watches and warnings, see our weather alert page.

Climate data from the federal government shows the Southwest has grown significantly hotter during the past decade. The region has endured the most pronounced warming in the country during that period, an increase that federal meteorologists said clearly reflects the influence of global warming.

In Phoenix and surrounding areas, developed areas have grown significantly hotter than the surrounding desert through the urban “heat-island” effect, in which exposed asphalt, concrete and roofs soak up heat from the sun and push temperatures higher.

In the know:What is the difference between heat stroke, heat exhaustion and dehydration?

Hot weather tips

The Arizona Department of Health Services has tips to prevent heat-related illness:

• Drink water: Drink at least 2 liters of water per day if staying inside all day. Those who spend time outdoors should drink 1 to 2 liters per hour they are outside.
• Dress for the heat: Wear light-weight and light-colored clothing. Sunscreen should always be applied to exposed skin. Wear a hat or use an umbrella when outdoors.
• Eat small meals and eat more often: Avoid foods high in protein that increase metabolic heat.
• Monitor those at risk: Check on friends, family or others for signs of heat exhaustion or heat stroke.
• Slow down: Do strenuous activity only during the coolest hours of the day, between 4 and 7 a.m.
• Stay indoors.
• Take breaks: Take a break in a cool place when doing physical activity outside on a hot day.

This article was generated by The Arizona Republic and USA TODAY Network using data released by the National Weather Service. It was edited by a staff member.