Whether you're at a pool, at the beach or planning on attending a Fourth of July parade and fireworks show, it's going to be hot day.

The entire Washington, DC, metro region, including Montgomery and Prince George's counties, are under a heat advisory, according to the National Weather Service (NWS).

Although temperatures will remain between 90 and 100 degrees across the region, the heat index could reach 105 degrees. The heat advisory will remain in effect until 9 p.m. Wednesday evening.

"The combination of hot temperatures and high humidity will combine to create a situation in which heat illnesses are possible," the forecasters wrote.

NWS asks people to stay out of the sun, stay hydrated, cool off in air-conditioning where available and check on relatives and neighbors without power.

If you will be outdoors today, here are a few tips from NWS:

• Sit in the shade under a tree or umbrella, if available.
• Drink plenty of water.
• Plan outdoor activities early in the morning or late in the evening.
• Wear loose-fitting and light-colored clothing.
• Be aware of the symptoms of heat stroke and heat illnesses.

Remember to keep pets safe, too, preferably in a cool area with plenty of water.