06/30/2026
June 29, 2026
Dangerous Heat - Wednesday through Saturday 3:00 PM EDT
Key Messages:
● High temperatures Wednesday through Saturday 95-105°F for most areas (hottest days look to be Thursday and Friday), then some cooling mainly on Sunday. Overnight low temperatures only dropping into the mid 70s to low 80s will offer little to no relief.
● Heat index values are forecast to be between 100-110°F Wednesday through Saturday, with the heat starting to ease some on Sunday.
● Some thunderstorms will be possible mostly during the afternoon and evening of Friday, Saturday and Sunday. If they occur, they will offer some local relief.
● The combination of very hot and humid conditions (near record breaking) for multiple consecutive days will increase the risk for heat related illnesses, especially for the elderly and the young.
Forecast Maximum Heat Indices
Forecast Maximum Heat Indices
Forecast Maximum Heat Indices
Heat Risk for Friday, July 3
heat-related illnesses for the entire population - this is a prolonged heat event that is very dangerous unless precautions are taken.
Little to no relief at night. Air conditioning is necessary - fans and open windows at night will not be enough.
Actions to take:
● Drink plenty of water
● Wear lightweight, light-colored clothing
● Cancel outdoor activities
● Stay in an air conditioned place, including overnight
weather.gov/phi
National Weather Service · Philadelphia/Mount Holly Updated: Mon Jun 29, 2026 3:00 PM
100°F Climate Stats
Location Most Recent 100°F Day Most # of
Consecutive
100°F Days Most Recent 2+
Consecutive
100°F Days Climatological
Probability of
100°F Occuring in any Year All Time
Record High
Allentown July 22, 2011 3 days
7/9-11/1936 & 7/2-4/1966 7/21-22/2011 16% 105° (Jul 3, 1966)
AC Airport June 25, 2025 3 days
7/2-4/1966 & 7/22-24/2011 7/22-24/2025 21% 106° (Jun 28, 1969)
AC Marina July 5, 1999 1 day
Occurred multiple times -
Severe thunderstorms may bring damaging winds, a couple of tornadoes, and heavy rain across portions of the Mid-Atlantic into the Mid-South. Severe storms may produce hail across the northern/central High Plains. Hazardous heat will linger across the southern U.S. and build across the West through m...