I'd like to grow an olive tree in my yard, but I'm concerned about the climate / winters. Boston is roughly on the same lattitude as the Mediterranean, but I think our winters are harsher. Thanks!

It gets a little too cold in boston. The winters will give the tree frost bite and it will die.

I had an olive tree planted in my front yard in Phoenix, AZ. but it is not going to tolerate the winters in Boston. Olive trees (Olea europaea) can only tolerate cold down to around 15 degrees F without suffering any damage from the cold. From the USDA cold hardiness map, it looks like your winters can reach average lows of -18 to -23 degrees F. This is enough cold to outright kill this tree when planted outdoors.