I have made a number of steam beers. I have done it in the peak of summer, where my basement can reach as high as 70, and I have done it in the depths of winter where we hit 58-60 in my basement. Both have been almost identical. I could not have picked out a real difference to be honest.
I am sure someone could have noted a difference between the two side by side. But not me. It is one of my favorite beers to date. And I plan on brewing another ten during christmas vacation.