Philadelphia hit 98°F at Philadelphia International Airport on Tuesday afternoon, breaking the city's all-time record high temperature for the month of May, the National Weather Service confirmed. The previous record, 97°F, had stood since 31 May 1991. With Tuesday marking the third consecutive day above 90°F, the city is now officially in the first heat wave of 2026.
The heat dome pushing into the eastern seaboard extends from Virginia through New York and was driven by an unusually persistent ridge of high pressure over the western Atlantic. Newark recorded 96°F, Washington National 95°F, and at least seven smaller stations across Maryland and Delaware broke single-day records.
Conditions are expected to ease slightly on Wednesday as a cold front advances from the Ohio Valley. The Storm Prediction Center has placed the Philadelphia metro under a Slight Risk for severe thunderstorms in the late afternoon, with damaging wind gusts to 65 mph the principal threat. Localised flooding is possible across the I-95 corridor.
Mayor Cherelle Parker activated the city's heat emergency protocol on Sunday, opening additional cooling centres at municipal buildings and extending the operating hours of all twenty-nine free public-pool sites. SEPTA reported a temporary speed restriction on the Wilmington/Newark Regional Rail line for fear of rail-buckle on continuous welded sections that had not yet seen their first heat cycle of the year.
Philadelphia Electric reported peak load of 11,420 MW on Tuesday afternoon, comfortably within capacity but the highest demand recorded in May. No rolling outages were ordered. ER attendances for heat-related complaints across the city's major hospital systems rose roughly 35 per cent above seasonal baseline, the city's health department said.