This winter, haunting signs of climate change were everywhere

As spring officially began on Monday, here’s a look back at the season.

This winter tied with 2015 to 2016 for Massachusetts’ warmest on record, according to data from the National Centers for Environmental Information. Between December and February, the months meteorologists use to measure winter, temperatures averaged 33.7 degrees Fahrenheit — nearly 8 degrees above the 1901 to 2000 average.

On Feb. 16, Boston reached 62 degrees, breaking a record high for that date, initially set in 1882 and matched in 1910, according to the National Weather Service.

The unseasonably warm weather created surreal scenes. Maple sugaring season, which usually begins in late February or early March, began for some producers a month early, and spring wildflowers like delicate white snowdrops and brilliant yellow aconite, were in full bloom by February.

Meteorological winter was mild across the United States, with an average temperature of 34.9 degrees Fahrenheit, or 2.7 degrees above average.

Connecticut, Kentucky, Maryland, New Jersey, Ohio, Virginia, and West Virginia saw their second-warmest winters, and for 21 other states, this winter ranked in the top 10 warmest.

Winter temperatures skyrocketed elsewhere around the Globe, too. India recorded its highest ever maximum February temperature. Some Chinese cities saw record warmth in January. And Europe experienced its second warmest winter on record, European Union scientists said last week.

In late December and early January, Europe endured a stunning winter heat wave, which smashed thousands of local temperature records in countries such as France and Hungary. Temperatures in the Netherlands, Liechtenstein, Lithuania, Latvia, Czech Republic, Poland, Denmark, and Belarus even broke national records. The unseasonably warm winter weather alarmed experts.

For some people, the warmth was a nice reprieve from otherwise-frigid winter temperatures. Many across North America rang in the New Year in T-shirts and light jackets. But the heat wave also had troubling effects.

In Italy, which last year declared a state of emergency last year amid its worst drought in 70 years, the high temperatures, combined with little precipitation, sparked concerns about water. Lake Garda in northern Italy reached record lows. The River Po, fed by snow from the Alps and spring rainfall, fell to disturbingly low levels. Unusually low water levels in Venice also dried up the lagoon city’s canals.

The unseasonably warm weather was peppered with moments of extreme cold.

In early February, the wind chill on New Hampshire’s Mount Washington fell to an all-time record low for the entire United States — a reported 108 degrees below zero. The previous coldest wind chill reported in the country was minus 105 degrees in Alaska.

The stunningly frigid conditions came after weeks of mild weather in New England. This fluctuation between temperature extremes — “weather whiplash,” as some experts call it — is becoming more common due to climate change.

It’s not just New England that saw these oscillations. Just days after parts of northern China experienced their lowest temperatures on record, southern Chinese cities broke records for high temperatures in January.

New England saw little snow this winter, with Boston receiving almost 70 percent less than normal.

Skiing attractions — such as Ski Bradford, a small resort near the New Hampshire border in Haverhill — opened fewer trails. And the beloved Mad River Glen resort in Waitsfield, Vt., was forced to suspend operations for weeks.

Ski resorts can rely on artificial snow in the absence of the real thing. But in some places, the mild winter conditions — especially the relatively high nighttime temperatures — made it hard to keep the fake flakes frozen, too.

It’s a business that’s “so dependent on mother nature,” Dennis Gauvin, ski patrol director of Haverhill’s Ski Bradford, told the Globe in late January.

The season also brought shockingly little snow to other parts of the country, too. Nearly snow-free slopes in New York, Virginia, and Pennsylvania sent shockwaves through the winter sports industry, as many trails were forced to close.

Across the Atlantic, the Alps were similarly starved of snow. Dozens of ski runs were forced to shut down, and some resorts — including those in Italy, France, Austria, Switzerland, and Bosnia — closed for the season. And a race was canceled at January’s Ski World Cup in Zagreb, Croatia, the Independent reported.

In February, top skiers wrote an open letter to the International Ski and Snowboard Federation, demanding action on climate change and more sustainable shifts to sporting schedules.

“The seasons have shifted,” they wrote. “Our sport is threatened existentially.”

In New England, ponds refused to ice over, delaying skating seasons.

Turner Pond in Walpole remained closed for skating this entire winter. Management allows skating only when the ice is 5 inches thick. That doesn’t usually happen until the weather stays around freezing or colder for nine consecutive days — conditions the town has not seen at all this winter, said Dan Ryan, chairman of the Walpole Pond Management Committee.

“Strangest winter we’ve seen since,” he said.

In Vermont, three ice fishermen died over three days after falling through the ice on Lake Champlain.

Soon after, an ice fishing tournament planned for the lake was canceled due to perilous conditions.

Several other similar competitions across New England were called off, too. And in Laconia, N.H., the 94th annual World Championship Sled Dog Derby was scrapped due to warm temperatures and lack of snow coverage.

It’s not just New England. The Great Lakes’ ice coverage hit a record low at a time when it usually sees the most ice. Ice on the Great Lakes has already seen a 70 percent decline between 1973 and 2017, according to federal data.

A lack of ice can leave shorelines around the Great Lakes exposed, experts say, leaving them more vulnerable to flooding and erosion, and severe lake-effect snowstorms — like the deadly one that hit Buffalo in December.

In late February, a weather system from the Arctic swept southern California, triggering the National Weather Service’s Los Angeles office to issue its first blizzard warning since 1989.

Snowflakes coated the Hollywood sign and the Santa Cruz Mountains. Trees were toppled and power lines fell, causing power outages for thousands of people. And while some regions’ ski slopes saw too little snow to open, in California, some ski areas were forced to close in order to dig out their ski lifts.

California is on the frontlines of the climate crisis, with drought and heat increasing. But experts say the winter’s snow was probably not related to climate change. The blizzard was mostly triggered by two factors: a large temperature difference between the North Pole and equator, which climate change is actually making smaller, and the rotation of the Earth, on which climate change has had little impact, Ned Kleiner, PhD candidate at Harvard studying atmospheric science, wrote in the Los Angeles Times.

Dharna Noor can be reached at dharna.noor@globe.com. Follow her on Twitter @dharnanoor.