Raleigh, N.C. — Data released Wednesday by the Department of Health and Human Services serves as a reminder of the dangers associated with extremely hot weather.

More than 690 people across the state sought medical treatment for a heat-related illness from July 11-25.

The average high temperature for July is 89 degrees, but during the period between July 1 and 15, six days saw temperatures in the Triangle topping 100 degrees, WRAL Chief Meteorologist Greg Fishel said.

The heat index, which indicates how hot it actually feels, soared even higher.

The heat index is driven by high humidity, which can also cause heat-related health problems. High humidity keeps perspiration from evaporating, preventing the body from cooling down. That leads to heat-related illnesses.

People suffering from heat exhaustion will often experience disorientation, muscle cramps, excessive sweating, fainting, nausea or vomiting.

Warning signs of a heat stroke, which can be fatal, include headache, dizziness, nausea, lack of sweat, rapid heart-rate, kidney failure and other organs shutting down.

To help prevent a heat-related illness, doctors suggest people start hydrating as early as possible before going out in the heat.

People should also avoid being outside during the mid to late afternoon, when temperatures are typically the highest, Fishel said.

The high temperature Thursday will be in the mid 90s, WRAL meteorologist Mike Maze said.

The weekend will be a bit cooler with highs in the low 90s.