In my livetime I've gone from Z3 to 4b/5a proximity. Accounting for the 50 year cycle, it will be interesting to see if we hit -34F again. I hope not.
As far as the hundred year cycle, is concerned, I'll worry about that when the time comes. :)

One interestting point however, My neighbor at the bottom of the hill, near the river's elevation, can actually be 8 degrees colder, by our 'unofficial' observations. I'm located on a ridge, perhaps 1000ft higher, and I have fewer frosts as well.

I heard about the changes but hadn't seen a map yet, thanks wirosarian! So now I'm 4b from 4a, although I had sort of figured that out the past few years. Maybe I'll throw caution to the wind and order that peach tree.

I actually got reliant peaches that I ate last summer. Planting on the east side of the house is recommended, but the biggest drawback is the 'canker' disease. I wasn't able to eat a complete unblemished peach because of canker, but still, better than nothing IMO.