This link (http://energycode.pnl.gov/EnergyCodeReqs/) takes you to a page where state maps with counties color coded to the climate zone type are available. Handy for planning what is best for insulation and vapor barriers for example.
This info is also available in the IRC, Chapter 11. That chapter also has a list that gives climate zone by State and County.
A little common sense and local knowledge can be invaluable along with the maps and tables. The county I live in is rated as climate zone 5B. We live 2.5 miles from the southern boundary of our county. It is a very large county, extending some 60 miles north. The county to the south is rated as climate zone 4B. There is enough of a difference between the two zones to matter with some things. The type of Hardi cement board siding is one.
Adding a Map... Map is clickable and enlargeable.
Another method for obtaining climate zone information. HERE (http://en.openei.org/wiki/ASHRAE_Climate_Zones) you can select the climate zone and zone sub type. Clicking on the link opens a page that lists counties in alphabetic order.
Nice maps Don.
It's amazing that Whidbey Island is further North than Maine but our climate is closer to Northern California. (Thanks to ocean currents and the jet stream.)
Here's a document that has a Canadian Snow Load MAp, see page 5 (http://www.nrc-cnrc.gc.ca/obj/irc/doc/pubs/rp/rp366/rp366.pdf)
and this ,,,, (http://www.canadiangeographic.ca/Magazine/jf03/alacarte.asp)
A climate zone map (http://www.greenbuildingadvisor.com/climate-zone-map-including-canada) that covers both the USA and Canada....