Well, I am in southwest Iowa and I plan on being on rollers through February, or at least a few good rains to get the sand/salt/crap off of the streets and especially in the corners where it is the easiest to crash. If you are only riding bike trails it wouldn't be so bad.
I have been riding on my rollers since December. This is a personal decision, and I think you really need to look at the streets you will be riding to see if they are clear enough.
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2007 Jamis Ventura Comp
2006 Jamis Explorer 2.0
2000 Specialized Hardrock (bought used)
Swim, Bike, Run and sounds like fun