Stay cool and hydrated during the excessive heat warning. Photo by Jim Headley

The National Weather Service in Phoenix has issued an excessive heat warning, from 10 a.m. Tuesday through 8 p.m. Thursday.

An excessive heat warning means that a period of very hot temperatures, even by local standards, will occur. Actions should be taken to lessen the impact of the extreme heat.

Today will be hot and sunny with a high near 108. Tonight will be mostly clear with a low around 77.

Tuesday is expected to be even hotter and mostly sunny with a high near 110 when the excessive heat warning is in effect. Tuesday night will be partly cloudy with a low around 78.

Wednesday will likely be sunny and hot with a high near 112 and maybe 113. Wednesday night will be mostly clear with a low around 78.

Thursday is forecast to be mostly sunny and hot with a high near 111 and winds 5 to 10 mph increasing to 10 to 15 mph in the afternoon. Winds could gust as high as 25 mph. Thursday night will be partly cloudy with a low around 72.

Friday will be sunny and cooler with a high of just 105 expected. Friday night will be clear with a low around 70.

Highs will remain above 100 through the weekend, so be careful outdoors. Take lots of water with you anytime to venture out of air-conditioned buildings.

During an excessive heat warning, overexposure can cause heat cramps and heat exhaustion to develop and, without intervention, can lead to heat stroke.

Stay indoors and seek air-conditioned buildings. Drink water, more than usual, and avoid dehydrating alcoholic, sugary, or caffeinated drinks. Dress for the heat – lightweight and light-colored clothing. Eat small meals and eat more often. Monitor those with a higher vulnerability to heat, including small children and pets. Check in on family, friends, and neighbors, especially the elderly. If engaging in outdoor activity, take longer and more frequent breaks and avoid the hottest parts of the day. Never leave kids or pets unattended in cars.

Recognize the signs and symptoms of heat-related illness. Early signs include thirst and muscle cramps. Heat exhaustion may include: cool, moist, pale skin; headache; dizziness; weakness or exhaustion; nausea. The most serious illness is heat stroke, which may include: vomiting; confusion; throbbing headache; decreased alertness or loss of consciousness; high body temperature (above 105F); hot, dry skin; rapid, weak pulse; rapid, shallow breathing; seizures. Heat stroke can be deadly. Treat as an emergency and call 9 1 1.