It’s hot. But is it hot enough to fry an egg on the sidewalk? (2024)

But it is unlikely in the United States for there to be the right conditions outside to cook an egg right on a sidewalk, said Teresa Bals-Elsholz, chair of Valparaiso University’s department of geography and meteorology.

In the right conditions? “This isn’t going to be a two-to-three-minute egg,” she said.

She said that, even in the current extreme temperatures, concrete will only get to 120 or 125 degrees and blacktop asphalt would get to 140.

It takes about 158 degrees to firm up an egg, said Nenad Miljkovic, a mechanical engineering professor at University of Illinois at Urbana-Champaign. Egg whites coagulate between 144 and 149 degrees while the yolk coagulates between 149 and 158 degrees.

For a sidewalk cook, he said the hotter and more humid, the better. Ideally, it would be about 120 degrees outside and a humid day. “The egg has water content, so as the egg cooks, water can evaporate and cool the process via evaporation. The more humid the air, the lower the evaporation rate,” he said.

The hottest air temperature recorded was 134 degrees in 1913 in a California portion of Death Valley, according to the National Park Service.

The scientists said a big factor of surface heat is the albedo, or the amount of light reflection. That is part of what makes asphalt and sand at the beach so hot.

“We learn that walking around barefoot as kids,” Bals-Elsholz said.

That also unlocks a clue as to how the idea of cooking an egg on the sidewalk was formed.

The thought dates back at least to a June 11, 1899, article in the Atlanta Constitution, according to the Library of Congress.

Francis Henry Wade wrote an article titled “How to keep cool” in which he suggested wearing “cork helmets.” He also recommended not thinking about who may be the next president and to “avoid excitement of all kinds.”

But the article began by saying: “With the thermometer cavorting away up along the nineties, with the bricks of the sidewalks hot enough to fry eggs … ”

It make sense the phrase was created when sidewalks were brick, as compared to now with concrete sidewalks that are much less conductive, Bals-Elsholz said. Brick is porous and heats up well, which is why it has been used to build ovens for generations.

The sidewalks of Atlanta were indeed brick or sometimes hexagonal concrete pavers in 1899, said Melissa Hamblett, an urban planner with the City of Atlanta’s historic preservation studio.

As a child growing up about in McDonough about 25 miles south of Atlanta, she said she tried to cook an egg outside. She said her canvas was a concrete patio in their backyard. It didn’t work.

“I would like to try it on brick, though,” she said.