Summer in New York City always smells like hot garbage. But this year is even worse.

The smell of hot garbage in the morning, evening or afternoon is well-known to anyone who’s lived through a New York City summer.

But the familiar urban fragrance is especially pronounced and pervasive this year, partly because of the three heat waves that the city has already experienced.

“It is the most disgusting cocktail of all the worst smells I can think of,” said Ollie Robinson, a marketing manager who lives in Hell’s Kitchen and was tweeting about the smell last week. “The garbage is in there but so is a little bit of sewage, possibly some throw-up. It is bad and it is strong.”

“I was around last year and it wasn’t as bad as it is this year,” he added in a phone interview on Wednesday.

City data shows that 311 received more odor complaints from May 1 to July 23 of this year than during the same period in any year since 2010 — except for the stinky summer of 2022, when the city finally reinstituted street cleaning rules that had been relaxed for the pandemic.

Odor complaints to 311 include categories like “pigeon odor,” “sewer odor,” gas fumes and others.

“Over the last two years, the City of New York has made major changes to the management of 44 million pounds of trash placed out for collection each day, to fight the rats, to get our streets clean, and yes – deliberately focused on defeating the hot garbage smell,” wrote a spokesman for the city’s sanitation department, adding that "50% of that trash is required to be in containers."

Heat exacerbates smells in normal ways, such as by making food rot faster, said Steven DiMartino , a meteorologist based in Freehold, New Jersey. Beyond the heat, a different atmospheric feature can make smells linger longer and spread further than usual, he said.

“Temperatures have been above normal, but what has been really record-breaking and impressive has been the humidity, and that’s the key,” DiMartino said, calling this summer’s humidity levels “impressive.”

High levels of water vapor help disintegrate and diffuse odor molecules, making the air a soupy solution into which garbage dissolves from solid or liquid into pungent gas.

“The other week, where it literally felt like we were walking out into a sauna, that’s optimal conditions,” said DiMartino. A garbage truck that might have smelled up the whole block in normal weather now taints several blocks — and the smell can remain for much longer after the truck is gone.

Heat waves also create what’s called a temperature inversion, according to DiMartino. Cities that bake in the daytime sun quickly cool overnight, trapping a cool surface layer and any odors on the street below the hotter air above. DiMartino likens the phenomenon to a warm locker room with a laundry hamper full of hot, steaming sports uniforms.

“After a long day of practice, you throw your uniforms in the hamper, close the lid and just let it sweat,” he said. “Now when you open up the hamper, i.e., the garbage truck, that stink is really able to grow.”

That’s what New Yorkers are smelling this summer: high-growth bacteria in garbage being trapped at street level by a humid heat wave atmosphere.

Additionally, heat waves in the urban mid-Atlantic come with stagnant air and a lack of wind that can clear out smells, said DiMartino.

“That’s why people love going to the beach in the summer, you get that sea breeze effect,” he said.

For the rest of the summer, though, expect a few more cold fronts with low humidity and northwesterly winds. This weekend, when temperatures are expected to top out in the 80s, is set to offer a taste of that, DiMartino noted.

This story has been updated to include comment from the city's sanitation department.