"I have been but little in," said Ninian hastily...

I know the British idea of heat and the USAian idea of heat vary considerably, and for many reasons. But several commentators giving the play by play on English Premier League matches last weekend were commenting on how the players were struggling with the intense heat. As best I could tell, temperatures in London and Manchester (where several of the games were being played) weren't getting above 20*C. This seems rather far-fetched to be described as 'hot weather'. Can anyone shed any light on this (no heat, please...)?

[crossposted]