I like Michael Bush's idea - it is a great rule of thumb IF inspecting. But if you are just peeking into the inner cover or removing the inner cover and looking, you can go a lot lower than flying temps if your peek is short and none obtrusive (frame removal) of course, people in colder climates laugh at what I just said, because they wouldn't ever get into their hive until their short warm season if they didn't give a good look now and then.
Just curious Sherry, have you had mite problems last Fall that needs treating - becareful to NOT treat unless neccessary.
What really blows me away is that 700 mile round trip - my God. That's from here to Watkins Glen, NY a trip I will do in August and as much as I love Nascar Racing, and as much as I look forward to the trip - I hate to think of the drive. I know it is weird, a guy buys a semi-luxury motorcoach www.beemaster.com/bus.html
(for the new folks who haven't seen it) but I just hate driving in general. I don't mind TRIPS as much as daily driving - my rides recently to my father-in-law's hom (he passed away last month) is only 11 miles, but takes an incredible 1 hour to 1 hour 15 minutes to get to with local traffic. It is THAT kind of traffic I dispise.
I would not have trouble medicating the bees on a sunny day that is in the 40s if the wind is low especially. But a cold cloudy and windy day would make me wait just to be safe. I know Spring is going by quickly, we've had 4 cool days with minimal flights from the hives and the TREES are in major bloom now. If you asked me 2 weeks ago if this was going to happen I would NOT believe that each day is again in the low 50s and rainy, because 2 weeks ago it was 75-80 and sunny every day, but the trees were JUST starting to give up their pollen.
Good luck and I hope you get your bees closer some day. I know you are very athletic, this trip and what else you do while there might be a great trip if the weather cooperates.
By the way, good to see you around so much again, we missed you there for a while :)