June 29, 2026
Jon Tuleya/PhillyVoice
Philadelphia may see high temperatures over 100 degrees for multiple days in a row this week.
A heat watch will be in effect in southeastern Pennsylvania, southern New Jersey and Delaware from Wednesday afternoon through Saturday evening with temperatures expected to approach record highs, the National Weather Service said.
In Philadelphia, temperatures could push above 100 degrees for three straight days, including on the Fourth of July, with NWS saying feels-like temperatures could hit 111 degrees. Ray Martin, a meteorologist with the agency's Mount Holly office, called it the strongest heat wave the area has seen since 2011.
Here are the highs forecasted by NWS for the rest of the week for its monitoring station at the Philadelphia International Airport, along with the daily record and year it was set in parentheses.
• Tuesday, June 30: 90 (100 in 1964)
• Wednesday, July 1: 97 (99 in 1964)
• Thursday, July 2: 102 (100 in 1966)
• Friday, July 3: 104 (104 in 1966)
• Saturday, July 4: 101 (103 in 1966)
• Sunday, July 5: 95 (100 in 1999)
The heat index, which takes into account humidity and air for feels-like temperatures, will remain steadily in the 100s — with highs ranging from 105 degrees on Wednesday to 111 degrees on Friday.
Good afternoon! There have been no major changes to the forecast as we're still expecting several days of extreme heat starting Wednesday and lasting through Saturday. #PAWX #NJWX #MDWX #DEWX pic.twitter.com/J3u9oRdqPc
— NWS Mount Holly (@NWS_MountHolly) June 29, 2026
Philadelphia’s all-time high was 106 degrees on July 22, 2011. The longest stretch of consecutive 100-degree days in the city has been three straight, which occurred July 2-4, 1966, and July 8-10, 1993, according to the NWS. Temperatures last hit 100 degrees on June 24 last year, which was the area’s first triple-digit reading since 2012.
"It's a very impressive dome of heat coming across the area, the strongest we've seen in as much as 15 years," Martin said. "It looks worse than what we saw last summer, for sure."
While the heat wave is widespread, Philadelphia could see some of the highest temperatures in the region.
"Areas where it's almost all concrete and very little vegetation, those are the ones that really get slammed routinely on these kinds of events,” Martin said, referring to a condition known as the urban heat island effect. “That pavement will rapidly go above air temperatures. It’s going to be pavement temperatures toward maybe 150 degrees or more with this kind of heat.”
This week, overnight lows will drop to the mid-70s and low-80s, which will worsen the heat wave’s intensity in the daytime, Martin said.
“It’s not going to be a lot of relief overnight and that’s going to exacerbate the conditions because your body’s just not going to have that ability to cool,” he said. “Fortunately, it’s only lasting for a few days. But it’s going to be a lot for people to handle.”
Potential thunderstorms may provide a cooling effect over the weekend and conditions are expected to mostly subside by Sunday.
The dangerous heat levels coincide with the events in the city related to the country's 250th anniversary and the World Cup. FIFA Fan Festival organizers have already begun to adjust hours for the daily watch parties in Lemon Hill to accommodate for the dangerous conditions and SEPTA will begin to reduce speeds on Regional Rail lines to protect its infrastructure.
Officials are advising people to drink fluids, stay in air-conditioned spaces, keep physical activity to a minimum, avoid sun exposure, check up on relatives and neighbors, and utilize city resources like cooling centers if needed.
While heat waves typically pose a threat to elderly and younger populations, Martin said that more people are at risk of contracting a heat-related illness during this week’s scorcher.
“This is going to be a brutal one,” Martin said. “Even healthy people could be at risk with this one where if you’re out in the sun and trying to get some work done, we could see fatalities from that. So, this is not one to mess around with.”
