We're zone 5b. Last frost this year was first week of May and USDA says we're frost-free by May 15th but I've been told by those wiser than me to plan on June 1st for putting tomatoes out ;)
There will be snow on the ground by Christmas but it won't be terribly bad until then... of course, that's all relative. We moved here from Minneapolis and I was raised in upper Michigan (snowed on the 4th of July one year there!). We are going to try hoops with greenhouse plastic and frost cover to grow spinach, kale and beets year-round. I think I'll try cloches for some tomatoes next year too and see what happens.