Excessive heat warning for Phoenix through Thursday

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By Catherine Holland By Catherine Holland

PHOENIX – The Valley of the Sun will be living up to its name in the coming days. The National Weather Service has issued an excessive heat warning that will go into effect at 10 a.m. Tuesday and remain in effect through Thursday night.

That warning covers Yuma and the lower Colorado River valley, Yuma County, La Paz County and Maricopa County, including the greater Phoenix area. Northwest and north-central Pinal County, including Casa Grande, is also part of that warning.

It’s been several weeks since the NWS has issued a heat warning for Phoenix.

While the mercury is on the rise, the humidity should be dropping so it won’t feel quite as sticky outside.

Plan on a high of 110 degrees under mostly sunny skies in Phoenix on Tuesday, 111 on Wednesday (112 is possible), and back to 110 on Thursday.

Overnight lows won’t drop much below the upper 80s. When the lows stay that warm, we don’t have as much of a chance to cool down from the heat of the day.

With such extreme heat and so little chance to cool off, dehydration and heat-related illnesses become a very real danger – one that can sneak up on you quickly. Many times, people do not realize they’re dehydrated until they’re in real trouble.

Emergency-room doctors say excessive heat causes a handful of deaths in the Phoenix area every year. According to the NWS, heat is the No. 1 weather-related killer in the U.S., contrary to what many people think.

"On average, more people are killed by heat in the U.S. than are by tornadoes, hurricanes, floods, and lightning combined," according to the NWS website.

Symptoms of mild to moderate dehydration include a dry or sticky mouth, fatigue and lethargy, decreased urine output, dry skin, headache, constipation, dizziness. Cooling the body and drinking water or a sports drink can usually reverse the effects.

Severe dehydration, however, is another matter. Simple drinking water is not enough. It’s a medical emergency that requires a 911 call and immediate care at a hospital or urgent care clinic. Symptoms include, extreme thirst, irritability and confusion, very dry mouth, lack of sweating, little or no urination, sunken eyes, dry skin that has lost its elasticity, low blood pressure, rapid heartbeat, rapid breathing, fever and in the worst cases, delirium or unconsciousness.

Heat stroke occurs when the body's core temperature rises to 104 degrees or above. It can be fatal if not treated promptly.

“The danger signs are when you stop sweating,” said Dr. Nicholas Vasquez, explaining that the people most susceptible to heat-related illnesses are those who cannot get out of the heat, the very young, the elderly, and those with chronic medical conditions.

When it comes to dehydration and heat-related illnesses, the best defense is a good offense. Thirst is not a good indication of hydration so be sure to drink plenty of water throughout the day, particularly before and during any kind of exercise or exertion. It's best to avoid caffeine as it can exacerbate heat-related illnesses.

If you have to be outside, reschedule strenuous activities to early morning or evening if possible. Wear lightweight, loose, light-colored clothing. A wide-brimmed hat will help keep your head and body cool. Be sure to plan plenty of breaks in a shaded or air-conditioned area. Above all, make sure to hydrate.

Doctors suggest most people consume about four liters of water, which is slightly more than a gallon, throughout the day. If you're going to be working outside or exercising, you will need even more.

It's also important to replace the salt the body loses to perspiration. Sports drinks can be a good way to do that.

Hot summers are, of course, normal in Phoenix, but that doesn't make the heat less dangerous.

According to numbers from the NWS, Phoenix sees an average of 110 days each year when temperatures of 100 degrees or higher. That number drops to just 18 when looking at days where the mercury reaches 110 degrees or higher. Those generally are the days when the NWS issues excessive heat warnings.

Still, the reading on the thermometer is not the only factor used by the NWS when it comes to issuing such warnings. The NWS cites studies that indicate most people are better able to tolerate heat later in the summer because we have acclimated somewhat, including increasing our regular water intake to stay well-hydrated.

Despite summer acclimation, hotter-than-normal days, like the ones we'll be seeing Tuesday, Wednesday and Thursday, still pose a hazard.

Once we’re past Thursday, the daytime highs should drop a few degrees as we approach the weekend. Things should stay relatively dry as there are no monsoon storms in our forecast for the next six or seven days.