The honey bee is essentially dead at 4 degC low and 48 degC high. They can survive and revive lower temperature but their motor skills are permanently hampered and lifespan significantly shortened.
The queen has to be protected and maintained between 22 degC and 38 degC, else her fertility is destroyed. Drone layers and supercedures soon follow a temperature excursion out of that band.
Drones; same temperatures as the queen, for fertility.
Those are my starting points. My gate posts and fencelines, if you will.
Those are not exact numbers, but should be very close within a degC-ish for purpose of the discussion. (( References: technical anatomy sections of the more recent editions of The Hive and The Honey Bee (Dadant), technical papers from National Bee Research Centres, as well as observations/experience. ))
As for reduced SHB survival and prevalence as going North; the main factor I am told is that the cooler ambient seasonal soil temperatures hamper grub development and thus low to no reproduction SHB. Supportive observation is that we do see SHB occasionally in the migratory hives in spring/summer. No action is taken other than apiary quarantine, as the SHB soon disappear as quickly as they showed up. When winter comes, nothing survives. ( -27 degC here today and frost level a solid 6 ft deep. My last trip out to the lake ice fishing got to right to the end of my auger (36in) before the water welled up.