OK, there seem to not be a study on this portion of the SHB life cycle. The best information I have been able to come up with is: From William Meikle of the Carl Hayden Bee Research Center and Kieth Delaplane of The University of Georgia.
Dr. Meikle provided me with a .pdf document that studied the soil temperature effects on pupation. Basically they expected zero at soil temps of 59 degF or less.
Dr. Delaplane offer his best guess as an ambient temperature of 50 degF for the shutdown of egg hatching.
Looks like it will be February before I can install SBBs back on my hives and be able not to worry about SHB for a while. The expected high today is 73 degF.