As temperatures creep to their highest point for the summer, most should seek refuge indoors with a cool drink and plenty of air conditioning.

Meanwhile, Hall County inmates on road maintenance crews still have to face the heat, but with state-mandated breaks and gallons of water.

The National Weather Service issued a heat advisory from today until 5 a.m. Thursday, with a high temperature of 99 to 100 degrees predicted and a heat index of 105 to 110 degrees.

A heat advisory is called when the daily low temperature is expected to stay above 75 degrees and the heat index is between 105 and 110 degrees.

When the heat index climbs above 110, an excessive heat warning is issued, which hasn't happened in Gainesville in at least 15 years, meterologist Vaughn Smith said.

Today is the peak of the weeklong heat wave that began Monday and should break with rain this weekend, Smith added.

Excessive heat warnings were issued Tuesday around the central Savannah River region of Georgia, including North Augusta. Most of north and central Georgia are under a heat advisory.

On Tuesday, Construction and Drainage Supervisor Scott Barnhart from the road maintenance division of Hall County Public Works oversaw a team of three inmates laying an 18-inch cross drain pipe on White Sulphur Road. They began at 8:30 a.m., before temperatures began to climb.

By about 10:30 a.m., Barnhart and the inmates felt the heat.

Their work day was punctuated with frequent breaks and plenty of water. On a particularly hot day, a team of three inmates can easily polish off a five-gallon cooler, Barnhart said.

Even before the heat became oppressive, Barnhart made sure to keep the inmate workers hydrated.

"From the early morning, we make sure they start hydrating with water prior to beginning work, then keep them hydrated all day long, so that keeps them from heat exhaustion," he said.

On Monday, correctional institute officials and public works representatives held meetings to explain the warning signs of heat exhaustion and heat stroke and encourage frequent water breaks and rest, preferably in shaded areas, said Hall County Road Maintenance Supervisor Jimmy Hightower.

"We knew it was going to be a big heat wave," he said. "The biggest thing is taking more breaks."

Hall County Warden Avery Niles said for temperatures above 98 degrees, road crew supervisors must offer inmates 10-minute breaks every 15 minutes, in accordance with state correctional department policy.

Barnhart's crew stayed on the job until about 3:30 p.m. and left in good health after pacing themselves and staying hydrated throughout the day.

"They had their proper breaks and worked through it with no problem," he said.

For anyone working or playing outside on heat advisory days, it's important to notice signs of dehydration, heat stroke and heat exhaustion.

The Georgia Department of Health issued a press release Tuesday warning people in Georgia on the signs of heat exhaustion and stroke.

Heat exhaustion sufferers experience profuse sweating, pale skin that's cold and clammy to the touch, weak pulse, and possibly fainting and vomiting, the release said.

In contrast, heat stroke, which occurs when body temperatures skyrocket to 106 degrees or higher, includes hot dry skin, a strong, quick pulse and, in some cases, unconciousness.

Since June 1, the average daytime high temperatures have been about six degrees higher than previous summers, and lows have been one to two degrees above the average, state climatologist David Stooksbury said.

Stooksbury cited heat as the No. 1 cause of weather-related death, beating out hurricanes, tornadoes and earthquakes. Especially susceptible are the young, elderly, sick and those taking certain medications, including diuretics.

The heat is most intense in the afternoon, he added, so people should try to stay as sedentary as possible and head to an air-conditioned area after lunch.

"The old idea of an afternoon siesta has its place," he said.

Stooksbury said the early signs of heat stroke could also include slow thinking, lethargy and slow or inappropriate responses to questions.

"They can almost act kind of drunk," he said.

Heat stroke is a medical emergency, so if someone shows the warning signs a friend or family member should contact 911 immediately, he added.