All of my hamsters live in a shed outside which has no heating at anytime throughout the year.
As they are in there all year they adapt very well to the temperatures gradually dropping as winter approaches, and by the time the temperatures are at their coldest the hamsters are completely acclimatised - none of them hibernate either which is a good thing, although they do spend more time in bed and are less active (i'm sure i have read that there is a word for that - a kind of hibernation??)
They all get extra bedding and extra shavings and they all make themselves gigantic nests
In the summer, if it gets very hot, i put fans in there to cool them down. All of my hamsters, especially the Roborovskis, seem to be able to tolerate the cold much better then they can tolerate the heat - i suppose its a good thing we dont get much of a summer
I don't really think the temperature matters as long as the hamsters have plenty of time to adjust to whatever temperature they are in.
I think hamsters would get quite ill if they were moved about into different temperatures without having time to adjust.
Tammy x