You finally buy that seasonal or year-round home of your dreams on the beautiful Maine coast or on an island. Then you learn that insuring it against storm damage, fire or burglary can not only be costly, but sometimes, downright impossible.

“It’s getting a little more difficult,” admits Denise Hopkins of the J. Edward Knight insurance agency on Vinalhaven. Each insurance company has its own criteria to determine rates and, in some cases, whether it will even take on the risk.

Terri Wright, an agent with the State Farm agency in Yarmouth, echoed that observation.

“It’s very difficult to get homeowner’s insurance on island properties,” she said. “There’s a lot of companies that won’t write island properties at all.”

But it’s more than concerns about storms, though that is one worry for insurers. Small, volunteer fire departments that may be miles away from a home on a peninsula or island raise the risk. If a home is 1,000 feet or more from a hydrant, or five miles or more from a fire department’s station, a red flag goes up for insurers, Hopkins said.

Seasonal properties bring other worries. Those valued at $300,000 or more “are a bit more difficult to find coverage for,” Hopkins said. There are surprising thresholds for that coverage, too; if an island house is rented four weeks a year, insurers write policies. If it’s rented for 6-8 weeks, they may not.

Seasonal houses may be on unplowed roads, or so remote that a neighbor doesn’t notice when a tree falls on the roof during a winter storm, further raising concerns.

With rising sea levels and larger, more powerful storms predicted because of climate change, insurers must weigh that risk.

Having a caretaker responsible for checking on the seasonal house or having an electronic security system helps keep rates down, Hopkins said.

There was a period when State Farm was wary of insuring island and coastal homes, said Brian Crawford, a sector manager for State Farm based in New Jersey, said.

“Obviously, we’re concerned with storm surge” and exposure to wind, he said.

But the emerging sophistication of satellite mapping services has let insurers tailor their decisions to actual conditions. For example, a house that appears to be 50 feet from the high tide line on Vinalhaven could be seen as a high-risk for storm surge water damage. But if that house sits on a 30-foot high rocky bluff on Carver’s Harbor, the risk is quite different. Satellite mapping allows that assessment to be made.

“We have mapping tools that will tell us if it’s in a location we know we’ll have problems with,” said Wright.

And houses built on islands are designed for their environment.

“When people build their houses out here on the islands, they build them to sustain that kind of wind, because that’s what we get out here,” Hopkins said. In 15 years as an agent, “I’ve never seen a wind [damage] claim denied,” she said.

New owners of seasonal island homes are often shocked to find they pay the same insurance premium on the property as they do for their year-round home, even though the mainland house may be worth three times as much, Hopkins said.

Despite the variables coastal and island locations present, fire protection remains the overwhelming driver of cost, Crawford and Hopkins said.

Still, island living has some benefits on the insurance front. Hopkins said auto insurance will cost a lot more in Portland than on Vinalhaven.