I have not had any problems using TB2 down to about 45 deg F. I think on one occasion I pushed it to 40 deg F, but would be reluctant to go any lower than that for fear that the temp would drop after I left the shop (after shutting off the small portable heaters and Coleman lanterns, and usually with evening temps approaching fast).
Yesterday the shop started out at 32 deg F (freezing) with outside temp of 25 deg F. I did other things until the heaters brought it up to 45.
Today the morning temps were in the teens with no relief in sight, so I left my glue and polyurethane at home.