The thermometer at BWI Marshall Airport wasted no time rising toward 100 degrees Friday morning, jumping from 88 degrees to 94 degrees in a span of an hour by 10 a.m.
The airport hit the century mark by 2 p.m. and hit 101 degrees an hour later, with high humidity causing a heat index of 111 degrees. The day started out at a low of 77 degrees at BWI.
The National Weather Service issued an excessive heat warning for Baltimore City and southern Baltimore County effective 10:15 a.m. through 9 p.m. Heat indices of 110 to 115 degrees are expected. The temperature downtown at the Maryland Science Center reached 106 degrees by 4 p.m., with a head index of 116 degrees.
Despite the heat's intensity, the record for June 29 at BWI could be hard to beat at 105 degrees, hottest on record for Baltimore in June.
Still, the region was bearing down for dangerous heat that could span a week or more.
Maryland health officials activated a statewide heat plan for Friday, urging residents to seek relief from the heat and be wary of heatstroke and heat exhaustion. The plan is in effect for Central Maryland and the Eastern Shore through Sunday.
Baltimore health officials said they plan to open cooling centers Friday through Sunday; Anne Arundel County is opening cooling centers Friday through Monday.
Stay tuned for more updates on the mercury rising.