A burst of heat and humidity prompted early school closings and electricity-saving measures across the region Wednesday, but a snap back to fall-like weather lies ahead Friday and through the weekend.
Temperatures surged to highs of 95 degrees at Baltimore-Washington International Thurgood Marshall Airport and 98 degrees at the Maryland Science Center in the afternoon. High humidity made it feel as hot as 105 degrees downtown as high pressure over the eastern United States pumped warm, moist air up from the Gulf of Mexico.
Though the heat was unseasonable, as much as 15 degrees above normal, it was not a record. Sept. 11 is the latest date on record in Baltimore to hit 100 degrees, in 1983.
Baltimore City and Baltimore County public schools closed two hours early Wednesday, canceling after-school activities. Howard County schools canceled outdoor athletic events.
School officials said they made decisions to close schools and cancel events based on forecasts of temperatures nearing 100 degrees because many schools lack air conditioning. In Baltimore County, 40 percent of schools lack air-conditioning, but it would have been impractical to only close those schools, system spokesman Mychael Dickerson said.
Superintendent Dallas Dance said in a school system that covers 700 square miles, it would cost $40,000 a day to only close some schools, plus seriously inconveniencing families with children in different schools. Buses would have to do their routes twice in order to pick up children from non-air-conditioned schools and then air-conditioned schools two hours later.
"Currently it is cost prohibitive for us to do that," Dance said.
Parents and teachers have complained that temperatures in some classrooms can be well above the outside temperatures.
City school parents complained on Twitter and in emails about the short notice the school system gave them about the early closing.
Parents were emailed less than 45 minutes before the elementary schools were closing and called after the dismissal time, said Jennifer Lotz, the parent of a first-grader at Roland Park Elementary School.
"This decision seems like a very poor judgment call, and shows a real lack of understanding about the realities of a working parent's day and the consequences of this decision," Lotz said. "The hour or more of chaos imposed on the schools would have been much better spent in the classroom."
In the city, 92 of the system's 162 buildings have air conditioning, school officials said, adding that many of the systems "are unable to maintain adequate cooling" because they are old.
In a statement, officials says that the decision to close schools "must be a careful and deliberate one," and that they monitored the heat conditions throughout the morning.
They said that shortly before noon, "it became clear that our systems could not maintain the necessary level of comfort for our students and teachers to finish out the school day."
"We know that an early dismissal presents many challenges for our families, especially in a situation when the notification is late," the statement said. "We apologize to our families for the inconvenience."
As the heat dominated much of the eastern United States, power usage across the region surged to a record level for September. A new high of 144,370 megawatts of peak electricity demand was set Wednesday in the territory of PJM Interconnection, operator of the electricity grid that covers Maryland, 12 other states and the District of Columbia. That was 11 percent higher than peak demand in September 2012 and equaled 92 percent of the peak demand on the grid in July.
PJM ordered Baltimore Gas and Electric Co. and other utilities to cut energy usage as a result. BGE enacted its Peak Rewards program, which cycles off customers' air conditioners for portions of every hour in exchange for rebates.
The hot weather came after a meteorological summer (June through August) that was about average in terms of temperatures, though it was the coolest since 2009. Wednesday was the 26th day this year that reached 90 degrees or hotter at BWI; at this point last summer, there had been 45 days at or above 90 degrees at the airport.
Given that summer doesn't technically end until the autumnal equinox, the heat in mid-September isn't unusual, though normal highs this time of year are around 80 degrees.
Thirty years ago Wednesday, heat baked the region for a stretch of several days, including during the final home opener for the Baltimore Colts at Memorial Stadium. Record high temperatures for Sept. 10 and 11 in Baltimore both date to 1983.
"If Colt blood was boiling yesterday, it couldn't be blamed on John Elway alone," read the story in The Sun on Sept. 12, 1983. The temperature on the field was estimated at 110 to 115 degrees, and the Colts lost to the Denver Broncos, 17-10.
Highs in the lower 90s are expected Thursday, but cool, dry air coming down from Canada is forecast to arrive before daybreak Friday, bringing a chance of storms as it approaches Thursday afternoon.
The change in weather pattern will bring a nearly 50-degree swing in temperatures from Wednesday afternoon to Saturday morning. Highs Saturday could fail to break out of the 60s, with overnight lows in the 40s across much of the region.