I have been noticing in the past couple of months while the weather has been cold here, my range has been dropping. Nothing dramatic but significant enough to notice.
I just discovered a similar blog like mine from a Chevrolet Volt owner. He recently posted a graph showing the range drop in the Volt depending upon the weather. Patrick lives in the San Francisco Bay Area as I do, so his experiences are very similar to mine. It does not get particularly cold here, but enough to slightly limit the range.