I have commuted the last few winters without studded tires. You can survive without them just fine most of the time. That being said I am pondering an extra set of wheels with studded tires for those times they would be helpful.
Also, regular winter lows are around 15F so I would lower my temperature tolerance a tad.
Weather records:
http://www.crh.noaa.gov/bou/cli/climo.php