The cases and deaths from equatorial areas such as Ecuador, Colombia and northern Brazil prove by demonstration that warm temperature in and of itself doesn't block the spread of SARS-CoV-2. That observation doesn't prove temperate has no effect though - for example, it could be counterfactually the case that Colombia would have have many more cases if it were cooler. So it is interesting see indications that temperature and spread are in fact independent.
As far as people going outside and being around each other, I have also seen it mentioned that in cold weather, people might tend to bunch up together inside small buildings, with recirculated air that can distribute respiratory droplets around. So there seem to be arguments for cold weather being worse as well as arguments for warm weather being worse. Maybe it is just bad all the time.
People are short sighted
If anything, as that thumbnail suggests, summer will make it worse because people will go outside and be around each other.. Where I live, things were ok for a while as it hit at the tail end of winter, but already people are bitching about having their summer cancelled. As if death wouldn't cancel all future summers for them.