Agreed, several variables affect foraging times and temperatures. Dr. Gerry Loper and I once mated bees in a giant tent at SWRI in TX in October.  The bees were loath to fly due to cold temperatures, but DARPA wanted a test.  The  solution - I put heating pads on top of each hive, and some recently trapped pollen in a dish  of top of the heating pad.  Gerry was skeptical, but it got the bees up and out and we did have afternoon mating flights.
Our bi-directional bee counters have always shown the hives facing east, into the sun, usually go to work anywhere from 1/2 to 1 full hour before hives facing west.
In Montana, over-wintered colonies fly to flowers poking out of snow.  Similar sized colonies brought in from CA in the spring usually take 1-2 weeks before they start foraging early in the  morning, under cool conditions.  It seems that they have to learn to get up early - whereas the over-wintered colonies follow the axiom that the early bird gets the worm.

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