We measured the temp at SEPTA stations around Philadelphia

While the mercury cracks triple-digits above ground, the subway stays cool.

Compared to the above-ground air, SEPTA stations are relatively cool

Compared to the above-ground air, SEPTA stations are relatively cool

Danya Henninger / Billy Penn

Updated 12:25 p.m.

If you’re looking for a place to cool off in Philadelphia, there’s an underappreciated way to find respite: take a ride on the subway.

Even as this weekend’s heat wave turned city streets into serious sizzlers, SEPTA has managed to keep most train cars at a refreshingly low temp. Measurements taken Saturday afternoon showed train interiors hovering around 70 degrees Fahrenheit. But it’s not just the vehicles that are refrigerated.

In contrast with subway stations in some other cities, underground stops throughout Center City have stayed consistently frosty, at least compared to the fiery pavement above. That’s especially true for the Broad Street Line, where stations are averaging about five degrees cooler than those on the El, according to an informal Billy Penn survey.

Armed with an infrared thermometer gun, which we tested for accuracy against two thermostats, we headed out in the summer heat to capture some data.

Danya Henninger / Billy Penn

The device, which looks kind of like a snubnosed Star Trek phaser, bounces rays off solid surfaces to come up with its reading. Caveat: In an enclosed space, those numbers can be a few degrees hotter or cooler than the ambient air, depending on which direction the temperature is heading.

We started by checking what it was like above ground. At the intersection of Broad and Snyder around 2:30 p.m., sunny pavement was a scorching 137 degrees. The sidewalk was slightly less scary, at 108 in the sun and 92 in the shade.

If you’re walking your dog, they’ll appreciate getting to a park ASAP — a patch of grass at that same corner was in the high 80s instead.

Heading down into SEPTA land, things immediately cooled off. Cement in portions of the upper ticketing area at Snyder Station were a cool 67, and readings next to the tracks ranged from 75 to 77 degrees.

That trend held throughout most of the central part of the BSL, with only one stop maxing out above 80 degrees.

The east-west Market-Frankford Line is more used than the north-south Broad Street Line on the weekends. With lots of extra bodies passing through, it’s not entirely surprising to discover that MFL stations were slightly hotter, all hovering between 78 and 82 degrees, on average.

The sprawling concourse that connects the two lines and various trolleys beneath City Hall was also pretty chill, ranging from 69 to 82°F.

A SEPTA spokesperson was not immediately available for comment regarding target temperatures or protocols regarding the authority’s subway air conditioning systems.

Amtrak, meanwhile, kept its grand 30th Street Station waiting hall at a pleasing 69 degrees — a huge difference from the 130-degree sunny sidewalk outside its doors.

City Hall was another place Philadelphians found refreshing fun. While the granite covering most of Dilworth Park hit 115 degrees, the sprayground fountains took it down to just 89 degrees when covered with water.

Kids enjoyed cooling off in the Dilworth Park fountains during the heat wave

Kids enjoyed cooling off in the Dilworth Park fountains during the heat wave

Danya Henninger / Billy Penn

The weekend brought the region’s hottest temperatures since 2012, according to NBC10. On Friday, hundreds were evacuated from a Philadelphia retirement community after the air conditioning broke down. Bars and restaurants around the city have been offering heat wave specials. Things are set to cool off in the coming days, however, with the forecast keeping the mercury in the high 80s.

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Weather, SEPTA