My part of Connecticut is Zone 7a, which means that the coldest it got in those 30 years was between 0 and 5 deg. F. Other places in Zone 7a include Richmond VA, Asheville NC and Nashville TN. Virtually all of Kentucky is in Zone 6b, which is colder. Here's a map from USDA.
https://planthardiness.ars.usda.gov/PHZMWeb/Images/All_states_halfzones_poster_rgb_300dpi.pdf
According to that map, I'm in 7b, so howdy, neighbor!
The old house, which is less than 15 miles as the crow flies, is 7a.
FWIW, I don't think those charts mean the coldest it got was 0-5 deg F. I think what they did was took the lowest temp for each year, and averaged them. 2019-2020 has been a mild winter so far (and probably will finish that way since the bulk of it has passed, at least here in MD). But, low single digits are pretty common around here in the winter, and we've gone negative a few times (at least in 7a...haven't been here in 7b that long yet). The winter of '93-94 was about the worst I can remember for cold temps. We had a few nights where it got down to -12 or so!
I was curious about property taxes up there, so I pulled up some real estate listings on Zillow, for Milford. I found one house that was somewhat comparable to mine...similar vintage, similar square footage, and both have a pool. Similar price as well. Smaller lot in Milford, but out in the boonies, an extra large lot doesn't always command an extra-big price, unless you can subdivide...and I can't. Anyway, Zillow showed the Milford house's taxes at around $8800, for a house with a $640K asking price. My house, in Maryland, was $630K, and its taxes are around $4800. One notable difference is my house is on well/septic, whereas the Milford house is on city water/sewer, which is going to raise the property taxes.
So, while I always hear about areas up north hitting you up with high property tax bills, that actually doesn't sound *too* bad. I wouldn't be happy about paying an extra $4,000 per year in property taxes, but if I was living there, and happy otherwise, I wouldn't uproot my life just to save $4K (or even a bit more, since the typical CT transplant probably moves to a lower-cost state than MD!)
Just curious, how long is swimming pool season up there, do you know? In 2019, the earliest I went in was around mid-May, and I had it closed up on September 23. I probably could have kept it open a bit longer, but I wanted it closed up before the trees started dropping their leaves in full force. In 2018 I was late getting on a closing schedule with the pool company, and they weren't able to close it until October 31. I think the last time I actually went in it was early October, and it was really a hassle during that time, fishing all the leaves and crap out of it.