Mail carriers cheerfully walked their routes, unburdened by hats or coats or boots made for blizzards. Joggers ran beside the (unfrozen) Charles River in shorts, and swimmers leapt into the sea at L Street Beach. Middle-aged guys cruised Commonwealth Avenue in top-down convertibles.
Schoolchildren skipped onto buses without gigantic down parkas. Waving goodbye on un-snowy sidewalks, their mothers looked blissful in yoga pants and T-shirts.
Days before Christmas, something most peculiar was in the air here: warmth.
At midday Friday and into the weekend, the temperature was in the mid-50s, at least 20 degrees above what Bostonians expect at this time of year. Sounding vaguely disconcerted, radio and television weather reporters announced almost daily that the thermometer would "dip into the 40s" by nightfall.
At the peak of what ought to be muffler and mitten season, meteorologists were not the only ones expressing confusion.
Swans swam placidly across ponds that should have long since turned to ice. Scientists at the Mt. Washington weather station in New Hampshire spotted bear tracks, suggesting that the creatures were not hibernating, as they should be in mid-December. And around the region, lawns remained green and flowers bloomed.
"I have plants that are thriving that normally would have died," said Brenda Balon, a member of the garden club in suburban Needham, Mass. "My dianthus and snapdragons are flowering, and my butterfly bush looks pretty good too."
Balon's husband took their two children to be photographed with Santa in a sleigh a local merchant sets up outside every year. Instead of frosty Massachusetts, the family Christmas photo this year will look more like Florida, Balon said, with the kids in lightweight sweaters.
"When you're sitting with Santa and the sun is out, it's very bizarre if you're from New England," she said.
The balmy spell in December follows the fourth warmest November on record. Daily temperatures around Boston averaged 49.1 degrees, said meteorologist Neal Strauss of the National Weather Service here. Two light snowfalls in early December left no appreciable evidence: "Not enough even to whiten the ground," he said.
He said no snow was on the horizon for the next week, adding that it was too early for a Christmas forecast.
At the weather station atop Mt. Washington -- the highest spot in New England and normally one of the coldest -- weather observer Jim Salge attributed the unusual conditions to "a persistent storm over the Aleutians, which is allowing warm air to flow into Canada." Therefore, Salge said, "cold air really hasn't been able to build up in Canada, which is where our cold weather comes from."
Large New England ski resorts were making snow in anticipation of the Christmas rush. But warm ground temperatures threatened to turn the artificial snow to slush.
Owners of smaller ski areas were left with brown slopes -- and no customers.
"It's completely barren here," said Shawn Freeman, managing director of the Blue Hills Ski Area. The 632-foot recreation slope is in Canton, near Boston, alongside one of the area's major ring roadways. Its proximity to Boston has made Blue Hills a skiing and snow-boarding destination for many local families.
Freeman said temperatures had made it impossible to manufacture snow because the ground had not yet frozen. "Last year, we had one of the coldest Decembers on record, then it warmed up in January and February," he said. "I'm hoping the reverse will be true this year.... If we have a warm January and February, I can pretty much kiss the season goodbye."
Though consumers embraced reduced heating bills, firewood vendors had not made extra deliveries since November.
Not far from Harvard University, the nets at the Cambridge Tennis Club come down in early November to make way for an outdoor skating rink. Late last week, the skating area looked more like a wading pool. A sign reading "NO ICE" hung in the club's window.
As a child in western Massachusetts, Melissa Ludtke said her father would flood the front yard every winter to create a skating rink.
"And I can't remember a Christmas when we weren't skating on it," she said.
This year, Ludtke and her daughter skated outdoors on a rink whose ice was sustained by an elaborate cooling system.
Ludtke, who edits a magazine published at Harvard, said she worried that the mild temperatures signaled dangerous warming trends worldwide.
"We are in deep, deep trouble," Ludtke said of the unusual weather.
Bank teller Jay Geary said the threat of global warming crossed his mind as he slipped outside for a coffee break Friday, in shirt-sleeves. Nevertheless, Geary relished the rare opportunity to be outdoors in December, in Boston, without the layers of clothing.
"It's crazy," he said. "But I'm not complaining."