There is a wide variety of fruits that do well here but it is a selected group.
For instance on my neck of the woods often we get a January meldown; for a solid week or so we can get temperatures in the 40’s and a week later down to 0 again. Anything stupid enough to loose winter hardiness dies.
Plants also need to key on different markers to go dormant in the fall. Too much sunlight can keep them from getting ready for the winter.
Borderline plants may be hardy enough, their buds may not. This is the case with some hardy sweet cherry trees, they will come back in the spring but no flowers.
Things that wake up too early in the spring can get hit in the face with more cold temperatures.
Things that bloom in May? Can get hit with snow. Not a problem with haskaps, snow will not even drop the flowers.
45-mile an hour winds when the temperature is 0 will do a number on the hardiest of plants. Make that -25 and windy on a test year and you get to find out what’s really hardy.
Things that don’t like cold feet pretty much forget about it. I have dug up leafing haskaps whose rootball were still encased in ice so you know they are good.
You also get to cheat. I have hardy grapes, but I also have a not so hardy one on the south facing wall of the house. In the winter time I put an insulation panel on front and sides; between the house heat and shielded from the wind I can probably jump 2 zones.
Things that thrive are those that really really really like the sun, as in getting 18-hours a day of sunlight plus a few more of indirect light a day. The world record for cabbage is 138 pounds and that came from my neck of the woods. Here’s a much smaller baby somebody is trying to grow for the fair:
And then there are the things that will grow, bloom, set fruit, grow said fruit, and year after year come to nothing because if it is not ready by early September it will just freeze on the tree.
All in all it is not that bad. Sour cherries, tons of hardy apples, haskaps, saskatoons, currants, gooseberries, aronia, seaberries, cranberries, raspberries, the ones that have been around and know the weather are quite happy here. Then you always stick that plum or filbert tree somewhere because of the joy of that one year out of 10, that the spring is early enough, the summer warm enough, and the fall late enough, that you actually get to try some of that