Excessive heat warning through Thurs.; Aug. could be hottest ever

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PHOENIX – With another five days of excessive heat – highs of 110 degrees or more – in the forecast, we could be looking at the hottest August on record.

The National Weather Service has issued another excessive heat warning that will be in effect from 10 a.m. Monday through 8 p.m. Thursday.

Normally, Phoenix sees an average of 17 days of 110-plus highs. With 22 already this year plus the possibility of five more in the week ahead, we’re approaching the record of 32 days set in 2007.

While humidity levels are down, strong high pressure is building over the Southwest. That means serious heat.

“By this afternoon, it’s going to be anything but pleasant,” said 3TV meteorologist April Warnecke. “We’re looking at drier, hotter conditions for the week ahead.”

Plan on a high of 111 degrees under partly sunny skies Monday. That could tie the record for today’s date.

The mercury is going to creep up to 113 degrees on Tuesday and 114 Wednesday, which looks to be the hottest day of the week. The heat will likely continue as we head into the weekend with 112 forecast for Thursday and 110 for Friday.

Normally, August is when the heat of the summer starts to wind down a bit. The average high temperature for the month is generally about 104 degrees.

According to the National Weather Service, however, the first 20 days of August 2011 have been the hottest ever for the month. The daytime highs average out to about 107 degrees and things have not been cooling off too much at night. The average lows have been in the 86-degree range.

One of the most important things to remember during an excessive heat warning is to hydrate properly.

Longtime Valley residents are familiar with the dangers of heat-related illnesses.

Dehydration, however, can sneak up on anybody, and it can happen very quickly.

Visitors to Arizona who are often unfamiliar with the extreme summer heat and its potentially deadly effects are especially susceptible to dehydration.

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 moderate to mild dehydration include a dry or sticky mouth, fatigue and lethargy, decreased urine output, dry skin, headache, constipation, dizziness.

It’s important to remember that thirst is not a good way to gauge your need for water. By the time you’re thirsty, you’re probably already on your way to dehydration.

“You should be drinking earlier,” explained Dr. Art Mollen earlier in the summer. “Thirst is not the direct indicator that someone is dehydrated.”

Mild to moderate dehydration can usually be dealt with by taking in more fluids, especially water or some kind of electrolyte-balanced sports drink.

Severe dehydration, however, is another matter. 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.