On clear, mild summer mornings, whatever those are, the sun rises fat and woozy out of the East, shimmering in a pool of its own rays. But this past month, here and across the country, there has been something blunt and almost predatory about the sun the moment it frees itself from the horizon.

You can see it in the way New Yorkers try to hide from the sun, walking on the shady side of the street, ducking into the shadow of awnings and overhangs. Get caught in the afternoon sun, and it feels as though something hot and fierce has jumped on your shoulders and bitten your neck.

There has always been something mythic about New York summers, just as there is about Chicago winters. The asphalt melts, we gather on the rooftops hoping for a breeze, air-conditioners roar and spit, and men begin to envy the airy way that women get to dress. Within the myth — the open hydrants, the stoop-sitting, the damp-mopped foreheads — there has always been a real danger: heat exposure, the risk to shut-ins, a dangerous surge in power demands, uneasy tempers.

The more extreme the weather, the more people talk about it, as if talking were a biological signal that we are reaching our limit. But, this year, the conversation has a different tone, as if this heat wave, which has punished the West and is now punishing the East, were more than a temporary discomfort and part of an uncertain and conceivably more dangerous future.