The weather has long been the subject of the most prosaic conversations, but an unfamiliar edge has crept into those talks in New York City after superstorm Sandy, a 2012 of unprecedented warmth, and now another unseasonably mild January.

With temperatures holding in the 50s for the past week, New Yorkers have dined outdoors, played team sports in city parks and strolled around without jackets. But some said they can't help but feel a tinge of anxiety—or even guilt—that the warm spell is another sign of climate change.

Hula-hoop dancers enjoy mild temperatures on Saturday in Central Park. Claudio Papapietro for The Wall Street Journal

"It's nice, but it's scary at the same time," said Blake Marciniak, a 20-year-old student who was in Washington Square Park on Tuesday, lunching al fresco by the fountain. "When we walked outside, it was a happy surprise that it's not as cold as it could be. But it makes me question what's really going on."

It is a sentiment that Ben Orlove, an environmental anthropologist at Columbia University, has heard more of in the two months after Sandy, on social media and in conversations.

"It's good to be outside, but there's also the 'It just feels weird,'" Mr. Orlove said. "You don't mind the warm January, but you mind a beastly July."

The feeling was evident at a Manhattan cocktail party on Tuesday, at which the windows were kept open. One attendee, Jerry Seinfeld, the comedian and a longtime city resident, lamented the weather's lack of variety.

"That's how I know what month it is," Mr. Seinfeld said in an interview. "Barring natural disasters, I like all weather. I like periods of pain. I like to get blown around."

To be sure, an unseasonable day, week, or season doesn't necessarily have a relationship to climate change, a blanket-term scientists use to describe the warming of the planet over time and changes in typical global weather patterns.

"One particular winter is not necessarily driven by climate change," said Deke Arndt, the chief climate monitor at the National Oceanic and Atmospheric Administration's Climatic Data Center. But he added: "Climate change does threaten more records on the warm end over time, and unseasonable winters are the types of things we'd expect to occur more often as the world warms."

The temperatures of the past week were unseasonably warm in the 40s and 50s but they weren't record-breaking, like January 2012, when there were 60-degree days. The region's January average temperature is about 38 degrees. The forecast for the next eight to 14 days includes below-normal temperatures, so the warm spell could be a merely a blip this year.

But the feeling that climate change has become more palpable appears to be seeping into the public consciousness. Sandy pushed several New York politicians to talk about climate change, including Gov. Andrew Cuomo, who said in November that Sandy was "a wake-up call."

Regardless of their cause, the temperate days have caused some New Yorkers to respond with an unusual mix of glee and anxiety. What might have seemed a pleasant, if ephemeral, bout of spring now feels disconcerting to some.

"It's sad," said Kimberly Diaz, 34 years old, as she walked her dog on sunny day last week. "[Climate change] is affecting us in ways we're actually seeing."

Matthew Wozny, 20 years old, said he was unnerved by the weather, even as he played tennis in shorts in McCarren Park. He said he assuages his guilt by reminding himself, "I don't drive a car, I don't eat meat several days a week, and I try not to drink out of plastic bottles."

New York City weather has become fodder on social-media websites such as Twitter, where a user named Andrew Buraczenski wrote on Saturday about freezing temperatures in California compared with relatively balmy days in the East: "It's currently warmer in New York City than in Los Angeles. Can global warming be a localized thing? Then it wouldn't be global."

Plenty of New Yorkers have simply enjoyed the higher temperatures and opportunities to spend time outdoors. Lev Saltonstall, who works at the Union Square Farmer's Market, said the weather was "definitely a benefit" for business, adding that it is "too soon to worry."

Others have been moved to act. Phil Aroneanu, co-founder of 350, an environmental-advocacy organization in New York, said more people are volunteering and attending his group's events. "There's a nagging anxiety," he said. "It's not just, 'Wow, it's nice out.'"