In general I find my BG rises in the summer. However, whether this is due to the weather or not is difficult to tell.
I find when it is cold, I spend more time indoors, watching telly and cooking higher carb meals whereas in the summer I am outdoors, exercising more and eat more (low carb) salads.
So I am not sure whether it is the heat, the exercise or the food which affects my BG in summer.
I have an unproven theory that it is the stress of uncomfortable temperatures (for some this is "too hot" and for others this is "too cold") which causes rises of BG. As with all thing related to diabetes, we are all different, get stressed by different things and our BG is affected differently by different things.
However, when I see a trend of my BG rising or falling, I adjust my basal insulin accordingly and try to bring my BG back to "normality". This basal adjustment is much easer with a pump.
@DCUKMod I have never had to adjust my "bo
nus" rate but if we got bonuses for managing our diabetes, I am sure there are times when I get less bonus points.