The heat index throughout Maryland hit its highest level of the year yesterday as a blanket of sweltering dirty air continued to linger over the region, bringing dehydration, scorched lawns and overheated car engines.
Weather officials reported a high of 99 degrees at Baltimore-Washington International Airport yesterday. The heat index - a measurement that combines heat and humidity to reflect how hot it feels - hit 104 degrees, prompting the weather service to issue a heat warning through today.
Relief, however, might be on the way for the July Fourth holiday weekend. Forecasters predict a cold front will blow into Maryland from the north tonight, possibly bringing with it a welcome wave of showers.
Until that happens - there's a 40 percent chance of showers tonight - people should be wary of strenuous activity, experts say.
"This is not a record-breaking temperature, but it's a dangerous heat index," said Michelle Margraf, a National Weather Service meteorologist in Sterling, Va. "It's feeling like it's record highs."
Heat might have contributed to the death of a 24-year-old Frederick County firefighter recruit, who collapsed at 8:10 a.m.
Andrew James Waybright of Gettysburg, Pa., lost consciousness on the grounds of a firefighter training facility in Frederick on his third day as a recruit. Authorities, who said the heat index at the time was 80 degrees, are awaiting the results of an autopsy to determine the cause of death.
Area hospitals and health departments reported few other problems. And in spite of the heat, which tends to cook pollutants into a smoggy haze, air quality was only moderately bad yesterday and is expected to be about the same today.
Several communities continue to wrestle with drought; Carroll County announced yesterday that it is toughening its water restrictions. Summer school sessions in Baltimore City closed early yesterday due to heat. But the main problem that Marylanders have been facing is sticky, uncomfortable air.
"I'm dehydrated, irritated, combatant and confused," said an overheated Tim Smith, a 20-year-old Bel Air resident who was selling peaches yesterday at the weekly Towson Farmer's Market, where at least one sweltering merchant took cover under a sun-blocking tarp.
In Fells Point, people flocked to get ice cream cones as packed water taxis floated by, ferrying sweaty passengers to destinations around the harbor.
"It's like Florida - only hotter," said Nancy Yosh of Hackettstown, N.J., who spent the day sightseeing in Baltimore with her husband and their two sons, ages 10 and 12. "It's great, but they [the boys] want to leave and Daddy doesn't want to be here."
Forecasters said yesterday that they were pleasantly surprised that pollution did not reach unhealthy "code red" levels, as it did Monday and Tuesday. Maryland Department of the Environment ozone forecaster Michael Woodman said a wind from the northwest brought in cleaner air from Pennsylvania yesterday.
An air mass from the central Plains had brought temperatures in the mid-80s to the region Friday. With no wind to push it out, it lingered, becoming warmer and dirtier and stickier by the day.
"The sun is just beating down and cooking it just like a pot of water, so it's getting hotter every day," said Margraf, of the weather service. "It will keep doing that until we get something in there to push it out."
Heat has begun to pervade many layers of Maryland life, including highway travel.
The heat wave is being blamed for problems on the Dover Bridge over the Choptank River on the Eastern Shore, which clogged traffic on Route 331 in Tanyard after opening for some passing boats Tuesday. The bridge became stuck in the open position after metal apparently expanded in the heat, forcing traffic to use a detour for about 2 1/2 hours.
Officials with AAA Mid-Atlantic reported yesterday that the heat has contributed to an increase in the number of emergency road service calls. The agency typically gets about 2,600 road calls a day, but yesterday's tally exceeded 3,000.
The number of cars at Downs Memorial Park, a normally popular summer hangout on the Chesapeake Bay in Pasadena, was down noticeably yesterday.
"Usually by now we have 100 cars here and all the pavilions are rented," said park gate attendant Brenda Meyers, who counted 57 cars at the park and no pavilion rentals yesterday afternoon.
Gomsak and Linda Lunsford, of Glen Burnie, had just finished lunch after taking a bike ride in the park- twice around the 4-mile perimeter trail.
"One of the park rangers stopped us and wanted to make sure we weren't going to faint on the pavement," Lunsford said. "We usually go hiking, but decided to take it easy today."
Contributing to Maryland's water-related woes - drought conditions have curbed water availability in Baltimore and other areas - are a series of water main breaks in the city.
Officials report that the city has had 49 water main breaks since June 21, almost four a day. That's more than the city usually experiences for the whole month of January, when freeze-and-thaw cycles take their worst toll on the city's pipes.
Public works officials do not think the breaks are related to the heat and pointed to other factors: manufacturing defects, the age of pipes and ground that shifts with freezes and thaws.
"This is very unusual for this time of a year," said Department of Public Works spokesman Robert H. Murrow. "When we get into June or July, it's usually the low point for water main breaks in the year."
On the Eastern Shore, veteran weather observer John Swaine Jr., 80, has been measuring the rainfall at his backyard weather station in Royal Oak. He said to conditions as parched as this year's, you have to go back to 1930.
So far, Swaine's small corner of Talbot County has gotten 14.87 inches, almost seven inches below normal for the first half of the year.
"I don't think the heat is any record-breaker around here, but the drought might be," said Swaine. "There's the heat and the humidity and not much wind to stir it up. Right now, I see very little chance for rain, other than very scattered thunderstorms."
Three years ago on July Fourth, Columbia's River Hill community pool, which can hold 550 people, had to close its gates because it had reached capacity.
There didn't seem to be a chance of that this year.
About 30 people - mostly mothers and their children - splashed around a bit yesterday, looking haggard. There were no sunbathers.
"On code red days, the crowd is not as big as it is on nicer, regular days," said 21-year-old pool manager Josh Mazalewski, whose biggest concern was making sure his 10 on-duty life guards stayed cool. "Some of the moms are even leaving because it's too hot."
Camille Behrman of Clarksville was there because she had to be. Her three kids have swimming lessons at the pool four days a week.
"It's a bit too hot for me, but the kids don't mind," she said as she slathered on sunblock. "For them it's a social thing."
Jim Laver, director of the weather service's Climate Prediction Center in Camp Springs, which makes long-term predictions, said the drought is to blame for turning up the heat this week.
"When it's dry, it does tend to get hotter, because instead of the heat going into evaporating moisture on the ground, it goes into heating the air," he said.
Laver warned that this summer in Baltimore was expected to be typical - and that means a few more heat waves.
"This won't be the end of the 90-degree weather," he said. "It's just the beginning."
Sun staff writers Tricia Bishop, Heather Dewar, Chris Guy, Brendan Kearney, Sheridan Lyons, Ben Piven, Jackie Powder, Kate Shatzkin, Laura Vozzella and Childs Walker contributed to this article.