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.
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.
Smog is expected to reach unhealthy levels through the weekend. As of 2 p.m. ozone is at code red levels in Calvert County, Horn Point and southern Maryland.
Stay tuned for more updates on the mercury rising.
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