We had been at 11a, which I thought was a bit too warm. 10b sounds right.
And have no fear about these changes. The USDA has thoughtfully provided the following information :
If your hardiness zone has changed in this edition of the USDA Plant Hardiness Zone Map (PHZM), it does not mean you should start pulling plants out of your garden or change what you are growing. What is thriving in your yard will most likely continue to thrive.More info on how they derived these new zones.