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Laura Seitz, Deseret Morning News
Alex Muniz, a commuter rail line subcontractor, gulps down water while working at 200 South and 500 West in Salt Lake City. Precautions for working and playing in the heat include staying hydrated and wearing loose clothing that covers skin.

The adage "hotter than the Fourth of July" is the literal forecast for the Wasatch Front through the weekend, with each day expected to top the high of 98 degrees on July 4 in Salt Lake City.

The National Weather Service forecast high temperatures for today at 103 degrees in the Salt Lake and Tooele valleys, with highs of 102 Saturday and in the upper 90s Sunday and Monday. Southern Utah saw record-breaking heat Wednesday and Thursday and may have seen an all-time record of 118 degrees south of St. George near the Utah-Arizona border.

The record won't be official until the equipment can be calibrated and checked, which could take several days. "But tentatively, the 118 will go down as the new all-time maximum temperature for Utah," said Larry Dunn, meteorologist in charge of the weather service's Salt Lake City office.

The previous record of 117 degrees was set on July 25, 1985, in St. George.

In Salt Lake City on Thursday, temperatures reached 97 degrees, falling just seven short of the July 5 record of 104 degrees. In St. George, temperatures were recorded at 115 — just 2 degrees below the city's all-time high.

Logan, too, was just 2 degrees below its all-time high for the date, at 94 degrees, and Hanksville was within 5 degrees of its record at 108 degrees.

If there is good news for Utahns, it's that temperatures are expected to be even more extreme in some surrounding states, and conditions would be more uncomfortable in areas with higher humidity.

"When it's 100 degrees in Salt Lake City, you can do a lot more than if you were in Florida or Georgia," said Dr. Colin Grissom, a critical care physician at LDS Hospital and president-elect of the Wilderness Society.

Working, playing, exercising in the heat — just how much can the body take?

Much of the answer depends on precautions people take, such as drinking plenty of fluids and combating salt loss by eating salty foods or drinking sport beverages.

Loose-fitting, lightweight clothes help the body stay cooler than shorts and a tank top, Grissom said. "If there is lots of exposed skin and the sun is out, it increases the risk of heat exhaustion. Having a wide-brimmed hat that shades you and clothing that covers the skin helps keep the skin cool."

Just how much a person should drink to stay hydrated depends on several variables. "The maximum you'll drink on a sustained level (of activity) is about a liter an hour." That's if you went out for a run. For longer activities, such as hiking, a quarter to half-liter per hour should do it. "Listen to your body," he said. "If you're thirsty, you need to drink."

Grissom also suggests staying away from the sun during the hottest parts of the day. "The biggest issue is that people need to gauge their activity so they try to avoid being outside in the day in the 1 to 5 p.m. range."

Brent Milne, managing partner of Milne Brothers Roofing in Murray, said his workers plan their day around the weather forecast, starting as early as 6 a.m. if it's expected to be hot and fleeing the roof by noon, when asphalt shingles become too hot to handle.

Grissom said dizziness, extreme thirst or feeling lethargic are signs of heat exhaustion and a signal that the affected person needs to seek shade or get indoors. "From there, the body can recover on its own," he said. "Just stop and seek shade and hydrate and rest."

But if symptoms include being confused and disoriented, or a body temperature higher than 102 degrees, "it's heatstroke, and you have a medical emergency. That's the person you need to get to a hospital."

Dirty air, made worse by wildfires, also takes its toll on a person's health, especially if he or she already has medical weaknesses or is elderly. Air conditions in Davis, Salt Lake and Utah counties deteriorated during the day Thursday, with the Utah Department of Environmental Quality forecasting conditions through Saturday as unhealthy for sensitive groups.

Contributing: Rebecca Palmer, Deseret Morning News; Associated Press.

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