A tenement in the summer is a “fiery furnace”

Tenement's Hester Street, Everett Shinn
"'With the first hot nights in June police despatches, that record the killing of men and women by rolling off roofs and window-sills while asleep, announce that the time of greatest suffering among the poor is at hand,' wrote Jacob Riis in 1890 in How the Other Half Lives. Riis, a former newspaper reporter who immigrated to New York from Denmark 20 years earlier, hoped his book would open the city’s eyes to the lives of the city’s poorest—people who resided mainly in the cramped, filthy tenement districts of the Lower East Side. No season illustrated how harsh life was for these tenement dwellers than summer, or 'the heated term' in Gilded Age parlance. That’s when the heat and humidity turned their substandard homes into what Riis described as 'fiery furnaces,' forcing people to seek a cool breeze on flimsy roofs, shabby fire escapes, and filthy courtyards. ..."
Ephemeral New York

John Sloan, Summer Roof