Humidity is also a factor, and also context around the environment.

Some months or maybe a year ago, I watched a video on youtube of an American's first visit to the UK, starting in London.

He filmed semi-live, and in his first clip as he arrived in London he noted there was a 'heatwave' on which he then noted he thought was funny because the temperature was a regular summer temperature to his home state (I forgot what)

The temperature was in the low 30s (c) / (around 90 f)

As he laughed at how funny he thought it was that Brits found this 'too hot' my immediate thought was 'he does not yet realise the combination of humidity, lack of existence of AC in England, and the way our buildings our built to retain heat'

Sure enough, over the course of his next few videos, he appeared increasingly drenched in sweat (hair slicked to his head), shirtless, and constantly saying things like 'we need to get out of this heat, man' and 'we need to find some AC' and then saying he was unable to sleep at all that night because his hostel room was so unbearably hot.

(for a stat, less than 5% of homes in the UK have AC, and I do not personally know anyone who has it).

80-90% (or higher) humidity is also pretty common throughout the year - I run a de-humidifier most days in my home, to be able to maintain 60-70% humidity)