As the summer trudges forward, today and Tuesday's weather will reach heights that might force the National Weather Service to send out heat advisories.

According to the service's Web site, today's forecast of 96 degrees will have a heat index that could reach up to 104, which could cause heat-related illnesses, such as heat exhaustion, heatstroke or dehydration.

The Heat Index is the temperature the body feels when heat and humidity are combined, according to the service's Web site.

"Higher levels of humidity combined with high temperatures create it; it's the combined effects of the two," said Ernie Ostuno, a forecaster for the weather service in Grand Rapids.

During days with high heat indexes, it is suggested that people watch what they do outside.

"(Heat Index) means that if you are doing something outdoors where you're going to sweat a lot, you're going to become dehydrated if you don't drink enough water," Ostuno said.

To prevent heat-related illnesses from occurring, Ostuno said that it's important to participate in physical activity toward the evening when the sun is coming down.

"The problem is that people get dehydrated from overdoing it outside," he said. "If you go outside, drink a lot of water."

Beat the heat

According to the Olin Health Center Web site, heat related illnesses can be caused by long exposure to hot temperatures and limited fluid intake. The site suggests people take the following precautionary measures:

• Wear lightweight clothing that is loose.

• Drink water often (not just when you are thirsty).

• Avoid caffeine, alcohol or large amounts of sugar because they cause you to lose more body fluid.

• Limit outdoor activity.

• If you do become overheated, improve ventilation, which promotes sweat evaporation.

If you have the following symptoms after being outside, you may be suffering from heat exhaustion:

• Dizziness, fatigue, nausea, faintness, headache

• Moderately increased body temperature

• Paleness

• Rapid, weak pulse

• Fast, shallow breathing

• Muscle cramps

• Intense thirst

• Cool, moist skin

• If experiencing these symptoms, rest and drink cool, nonalcoholic beverages. You can also elevate your legs higher than your heart or take a cool shower or bath.