The field is at 5000' and it averages 70 degrees with low humidity and dew points around that time. We are probably running between 5000' and 6000' that time of year unless we get an unseasonably hot day it may go up, but so far this year it looks like we won't be making it over 6000' until later in the summer.
My EDF's 90mm Viper and 105mm SuperViper do good until about the end of May. They aren't necessarily heavier, but they fly heavier, but manageable, up here during that time.
My Boomerang Sprint is close to 30lbs and it does alright too, and those things fly like a tank with all that drag.