Every so often someone will ask me what we could possibly do here in the winter, spring and fall. The answer may well be that we do the best things we do all year. There will be beauty everywhere you look, especially beautiful light. There will be bright stars. There will solitude and safety and delicious peace and quiet. The air, depending on the time of year, will smell like snow, or like the cold ocean or like blooming shad, which covers Rodman's Hollow with tiny white flowers, so many that it looks like it's snowing, and which make the air smell like roses.
Generally speaking, just be sure to watch the ferry schedule as it winnows down and down until some days, there is only one boat running, and depending on weather, it's possible that it won't run at all. Be prepared to stay the night, as you often can't get on and off of the island on the same day. Also check the Interstate Navigation website. (Here is the link: https://www.blockislandferry.com/) You should have choices, give or take a day, to enable you to bring your car on and off the island.
You should be able to pay less money for your accommodations than you do in the summer, especially for long-term stays. The Block Island Chamber of Commerce can give you information on Hotels, Inns and B+B's. They can tell you which ones are open, and whether they have availability or not. (Link: http://www.blockislandchamber.com/), They can also lead you directly to realtors.
Most of the shops, the theaters and restaurants will be closed after Columbus Day Weekend and into late spring There will be a few exceptions. You will be able to get breakfast and lunch at Bethany's AIrport Diner, as well as sandwiches, some pre-made items, and some hot foods at the Block Island Grocery Store (The BIG), which will be open every day. Pot's and Kettles, a truly wonderful food truck, should be open. Some restaurants may be open at other times. That changes. Check the Block Island Times or the Chamber of Commerce for that information. Believe it or not, you can actually get take-out food sent over from Westerly on the plane. Here's the link for New England Air. http://blockislandsairline.com/ The gas station will close in the early afternoon and if the ferries don't run for a few days, they may run out of the kind of gas you want. You'll be able to get taxis. The Chamber can tell you if mopeds or bikes will be available at the time of year that you plan to come.
Shops and some restaurants will be open over Thanksgiving Weekend for the Christmas Stroll. Something might open especially for Christmas and also on Valentine's and Mother's Day. The Harbor Church will have a wonderful turkey dinner at Thanksgiving.
Depending on the time of year, there will be bird watching, running around the island, poetry readings, movies at the library, fishing, biking, surfing, photography, hiking and hunting (get an orange vest, check the hunting schedule, look out for trucks parked by the side of the road, and do your hiking on the beaches. If you're bringing a dog, get an orange vest for him too.) If you're going to hunt, you'll need a permit from the town.
For photographers, there will be swans for most of the winter, and blue heron, as well as lots of seagulls and tiny piping plovers. There will be cardinals and mourning doves and many other beautiful birds. Great white egrets will leave in the late fall and return in the spring. There might be snowy owls in the winter but please don't follow them around. They need to be undisturbed because if you cause them to fly when they don't want to, you'll expose them to crows, and those, working in groups, can kill them. They also need to sleep during the day. They're out of their normal range and can easily starve to death. Of course you'll have waves, beautiful waves, and the thing that makes them so beautiful on Block Island is the clarity of the water.
It will be warmer in the fall and early winter than it is on the mainland and cooler in the spring. Bring rain gear but don't bring an umbrella because if you open it, the wind might blow you right off the island. Bring a book. Bring tea. Be prepared for quiet and your own fascinating company. Bring things to do that you always wanted the time to do. Bring wool socks and sweaters. With notable exceptions for truly brutal conditions, think Ireland or England in the winter. Usually not too cold but very wet and windy.
You'll find it very different from what you will find in the summer. If you're up for some beauty and solitude, you might find that it is your favorite time to come.