Just be sure to brace yourself if you're going from one extreme to another! I was raised in southern Turkey, where the weather is balmy in winter and positively infernal in summer. You can cook eggs on the pavement, asphalt sticks to your soles like chewing gum, and people discharging guns at the sun after having a heat-induced mental breakdown is so common that the police have to arrest a few modern-day Hou Yis every year.
So when I was packing for a BPS meeting in Baltimore, I think back in 2019, I took a sweater and a light jacket and told myself the weather wouldn't be that bad. It was. Four days later I was presenting a poster while trying my best not to keel over, and my pride was only saved by the fact that one my fellows was hit just as hard by the kind of freak temperatures that allow ice to exist outside your fridge.
As for the fish, thankfully what I keep is hardy enough not to care unless the water starts to melt the bucket. Cold water gets the cories breeding, so I prefer it to the alternative.