The National Weather Service issued a heat advisory today for Washington, D.C., and parts of Virginia and Maryland, cautioning that high temperatures and humidity are creating potentially hazardous conditions.

The heat advisory remains in effect until 8 p.m. Tuesday, the agency said. It said the advisory could be upgraded to an excessive heat warning on Tuesday.

The heat advisory was declared as temperatures soared into the mid-90s, with high humidity adding to the discomfort. The weather service said heat indices were around 100 degrees this afternoon and that "even hotter conditions are expected on Tuesday." It said heat index values of more than 80 degrees are expected Tuesday night.

The heat advisory covered Northern Virginia from Winchester to Alexandria and much of Maryland, including Baltimore. The weather service said hot, hazy and humid conditions were expected over the region through mid-week.

While an excessive heat warning may be declared on Tuesday, especially for Washington, heat advisory conditions are expected to continue on Wednesday, the service said.

A heat advisory means high temperatures and humidity "combine to create a situation in which heat injuries are possible," the weather service said.

It urged people to drink plenty of fluids, stay out of the sun and check up on relatives and neighbors. The service also warned against leaving children or pets in cars with windows rolled up, even partially, since temperatures inside can quickly exceed 150 degrees, resulting in heat stroke and death.

Today's high temperature in Washington was pegged at 95 degrees. It is expected to get up to 98 degrees Tuesday.