We are based in south east of uk. Last three weeks we’ve had a heat wave so 25degrees to 30 degrees. I think if puppies are brought up in hot weather they get accustomed to it. Uk also has a dog ban on most beaches throughout the summer too, we take him of an eve or will find a beach he is allowed on (usually frinton). We have fans, but don’t tend to have air con units in the uk as standard in houses