Heat — Southern Baltimore, Maryland

1999-07-04 to 1999-07-07 · Southern Baltimore, Maryland

Wider weather episode

High pressure sat off the Mid-Atlantic coast from the 4th through the 7th, acting like a heat pump drawing in extremely warm and humid air. Temperatures on the 4th through early on the 7th were oppressively hot, and extremely humid conditions added to the misery. These conditions continued until a cold front swept through the area during the afternoon of the 7th, ushering cooler and much less humid air. The mercury soared into the upper 90s to lower 100s during the period. Dew points were in the lower to middle 70s, creating heat indices between 100 and 115 degrees. Nighttime lows only dipped into the 70s and heat index values remained in the upper 70s to middle 80s. Heat index values only dropped to between 85 to 90 degrees in downtown Baltimore. Record high temperatures were recorded at Baltimore/Washington International Airport (BWI) on the 5th and 6th. At BWI the mercury soared to 98 degrees on the 4th, 102 degrees on the 5th and 101 degrees on the 6th. Afternoon highs at the Maryland Science Center at Inner Harbor Baltimore rose to 99 degrees on the 4th, 101 degrees on the 5th, and 102 degrees on the 6th. The heat index only dropped to 90 degrees at Inner Harbor on the morning of the 6th. Other high temperatures from the 4th included 101 degrees at Bryans Road, 100 degrees at Ridge, 99 degrees at Williamsport, Smithsburg, and Oxon Hill; and 98 degrees at Cumberland, Hagerstown, and Olney. On the 5th, temperatures soared to 102 degrees at Oxon Hill and Ridge, 101 degrees at Smithsburg, 100 degrees at Cumberland, South Bowie, and Millersville, 99 degrees at Laurel, Hollywood, and Glenmont; and 98 degrees at Gaithersburg, Rockville, Sharpsburg, and Hagerstown. Highs on the 6th included 103 degrees at Ridge, 102 degrees at Lothian, 101 degrees at Olney, Rockville, and Glenmont, 100 degrees at Forest Glen and Hagerstown, and 99 degrees at Millersville, Laurel, Gaithersburg, and California. Because of the 4th of July holiday weekend, many people were inconvenienced by the oppressive conditions. Many holiday events had low attendance, with the exception of the late evening fireworks displays which occurred after the temperatures fell below 90 degrees. Those who spent considerable time outdoors or in non-air conditioned buildings were subject to heat related illnesses. The heat wave tragically killed 15 people in the city of Baltimore. The number of people treated for heat related illnesses included 21 in Anne Arundel County, 200 or more in the city of Baltimore, 6 in Montgomery County, 5 in Prince Georges County and Calvert County, 2 in Washington County, and 1 in Allegany and Frederick Counties. Road surfaces and cars also fell victim to the heat. A huge buckle on Columbia Pike in Howard County between Johns Hopkins Road and Route 216 forced the road to be closed. Interstate 70 in Western Maryland was littered with tractor-trailer tire caps as the heat caused the rubber to fly off the tire casings. State police reported 20 vehicles were disabled by the heat, and AAA responded to 600 heat related service calls across the state. Power companies reported record high energy consumption during the late afternoon of the 5th and 6th. High demand for electrical power blew transformers, leading to power outages for 17,000 customers. The city of Baltimore cancelled summer school classes on the 6th because many schools had no air conditioning. Washington County closed summer day camps on the 6th after several campers reported problems dealing with the heat. Baltimore County reported thousands of yellow perch were killed in the MIddle River watershed by the extreme rise in water temperature that occurred during the heat wave.

Source: NOAA Storm Events Database, event_id 5710710. Narrative written by the NWS forecast office that issued the report.