Part of an occasional series answering readers’ questions about Maine. 

Q: “When was the last time Portland Harbor froze over so you could walk to Peaks Island?”

A: Maine has long been characterized by its ferociously frigid winters and the persevering nature of its natives during the snowy season.

Nonetheless, it’s been some time since people trekked across ice to Casco Bay islands. And, even in the olden days, it was a rare event.

A search through newspaper clippings and archives unearthed a handful of headlines documenting frozen portions of Casco Bay, dating all the way back to the 19th century. In Nathan Gould’s book, “A History of Peaks Island and Its People,” he provides an early written record of a completely icebound Portland Harbor, and remarks on the more than two-mile expedition made by sleigh.

“The harbor is seldom frozen hard enough for persons (on Peaks) to cross the ice to the city,” Gould wrote. “The writer crossed on the ice from the city and returned the same way, Feb. 15, 1875. That day a sleigh with two persons went from the city and returned with safety.”

Throughout the early 1900s, venturesome Mainers were afforded a few opportunities to make the voyage across ice from the city to islands in Casco Bay.

In 1918, Maine endured a particularly frigid winter season. According to Donna Damon from the Chebeague Island Historical Society, a newlywed couple journeyed over nine miles from their wedding on Chebeague Island back to Portland on foot, taking a photo at every buoy they could find.

In February 1933, five young Mainers made a local splash after embarking for Portland from Chebeague Island in pursuit of the island’s supply of Maine Sunday Telegrams.

This Portland Press Herald story in February 1933 tells the story of five young men who drove a truck across the ice from Chebeague Island to the mainland to get the island’s supply of Sunday newspapers. The regular ferry couldn’t get through with supplies. Press Herald file photo

The Portland Press Herald reported that “[the boys] took off from the north side of the island, set a course in back of Cousins Island and then followed the main shore to Town Landing. Here they pushed and tugged the truck through deep snows, managed to reach the main highway and a short time later arrived with a flourish in front of the Press Herald building.”

The 1933 article also noted that while previous winters, like that of 1917-18, had allowed people to travel across the bay, this marked the first time that a truck had made the daring trip. They made the 14-mile journey in just forty-five minutes, and hold the unofficial record to this day.

The harbor partially froze again the following year.

A photo of the front page of the Feb. 26, 1934 edition of the Portland Press Herald shows a Casco Bay Lines ferry stuck in the ice more than 200 yards from Peaks Island. The boat’s passengers walked across the ice to get to the island. That frigid winter of 1934 saw many harbors around Casco Bay frozen solid.

Casco Bay Lines ferry Emita is shown in this Feb. 26, 1934 Press Herald photo stuck in the ice more than 200 yards from Peaks Island. Passsengers are shown walking across the ice to get to the island. Press Herald file photo

Nowadays, an ice-locked harbor is practically unheard of, outside of tales told by longtime inhabitants around Casco Bay.

Portland Harbor is much more apt to freeze than outer parts of the bay because of the fresh water introduced by the Fore River. But it generally doesn’t freeze because of both the salt content of the seawater and strong tides and currents. While fresh water freezes at 32 degrees, seawater doesn’t freeze until the temperature drops to 28.4 degrees. Abundant snow falls can help by building up a supply of fresh water at the surface.

There was little chance of ice this winter.

The average temperature during the past winter season – December through February –  was 30.1 degrees in Portland, making it the fourth warmest winter since such record keeping began in 1940, according to National Weather Service. The historical average is 25.6 degrees.

The mild temperatures over the past three months were a sharp contrast to just five years ago in 2015, when the winter air temperature averaged 22.9 degrees and ice formed across the harbor from the mouth of the Fore River to Bug Light in South Portland. While larger vessels such as ships and ferries were able to continue operating by pushing through the ice, fishing boats and other small vessels were forced to remain docked. In addition to the obstruction of boat traffic, the ice also caused damage to some marinas.

That winter of 2014-15 was believed to be the first time extensive ice had formed in the harbor in more than 30 years, and the average temperature in Portland hasn’t dipped that low in the years since. Given the trend toward milder winters and predictions of continued warming, icy strolls from Portland to Peaks Island are likely to remain the stuff of memories and history books.