Re: As a currently visiting antipodean....
Speaking as a Brit who has lived several years in much hotter climes ...
Hot - including Too Hot - here starts at mid-20s. The fact that's not at all hot to an Aussie is irrelevant: your whole environment is much better-suited to heat, and it feels natural there. I don't know why, but 25 in Blighty feels like 40 in Oz[1] or the Med[2].
Note - Brits complaining of cold can be even more unedifying. We don't get real cold here, any more than real heat.
[1] Based on a couple of weeks hols, when the only thing I really needed that I don't in Blighty was sunglasses.
[2] Based on several years in central Italy - yes I do have real experience of hot summers. Needed sunglasses there too.