Couple of data reasons for the big change, one sad reason:
We went from 8000 weather stations to over 12,000 so less estimating and more granular, accurate data. AND, the zones use 30 year averages. the 2012 map had some freak record cold years in it, and now, those have finally aged out of the averages. THUS, average temps are warmer...
... as well as overall, global climate change has been bringing us generally a climb in avg temps, here in MA. GOOD for us here in MA, but, not so good for some. Friends in San Diego, TX, and more can expect longer extended droughts, now.
That's cool info I didn't know! I know it seems warmer, but I sure would hate to plant stuff and have a frost or hail storm, like I did 5 or 7 years ago...
You've got a much bigger planting area... so you need to be careful. For me? I am still planting my 200 tomato seeds indoors, 24 pepper, 24 squash, and misc other stuff. I am not putting them outside any earlier. Just hoping I get an extra week or three in fall!
Me too!