With the mercury topping 90 degrees today, two area school systems sent pupils home early and officials advised people to be cautious if they planned to be outdoors for extended periods.
Forecasters at the National Weather Service in Sterling, Va., said soaring temperatures combined with high humidity to produce even more sultry conditions than yesterday, with heat index values expected to near the 100-degree mark.
A heat advisory was in effect until 6 p.m. for most of Maryland.
"It is advisable to wear lightweight clothing to keep cool and maintain a safe body temperature," said Calvin Meadows, a hydrometeorological technician at the weather service.
"In this weather, people are more susceptible to sunburn, heat cramps, heat exhaustion, and [in] extreme cases, heat stroke."
Officials advised people to stay inside air-conditioned buildings, drink fluids and avoid strenuous activity during the hottest parts of the day.
Harford County officials decided to close public schools three hours early today, and in Baltimore City, public schools closed two and a half hours early.
Tonight, showers and thunderstorms were possible, with lows in the mid-70s.
Temperatures tomorrow are expected to climb into the 90s again with a chance of showers and thunderstorms in the afternoon. But forecasters say some relief is in sight, with cooler air expected to move in by the end of the week, when highs will reach about 80 degrees.
June 14, 2005, 6:12 PM EDT