Pretty interesting. Mine has stayed the same. While most experienced bonsai folks are pretty in tune with the weather/climate and its effects, it's probably a good reminder for beginners to always be mindful what their trees are telling them about the weather/soil/water/everything in the environment.

Thanks for sharing Treebeard!

One thing to consider that Michael Hagerdorn recently did a blog post about is that hardiness zones (I'm paraphrasing) are good for trees in the ground not bonsai as the roots don't have the same insulation.  Obviously a good overwintering plan that protects your trees will negate risks.  One thing that is good to consider with new bonsai is where they came from; a tree from Florida now living in Ohio may not be as tough even if the species is "hardy" in both places.  When buying seed to grow bonsai, it's also a good idea to check the provenance (where the seed was collected) as seed from a colder locale is good to use.

Maybe they didn't bother updating us coastal folks since the data show we will clearly be underwater in a few years. Not worth the trouble...