Yesterday (Wed) seemed hot in the Southampton/New Forest area
yesterday (my guess was about 26C) yet the temperatures were
apparently only 20-22C, i.e. fairly normal, and slightly on the low
side of normal if anything. I suppose there have been so few days with
normal temperatures and sun this year that even that feels
exceptional... the perceived warmth is similar to that which you would
normally get in April on a sunny day with those temperatures.

Nick