The recent much welcomed hot spell makes an 8 hour day working on a roof uncomfortable and not surprisingly work rates do fall. I do have to remember though on a trip to Dubai in July 2008 watching steel erectors working hundreds of feet from the ground in 47°C in the shade and wondering how they could do it!?
As this photo shows the mercury is approaching 39° Celsius out of the shade. The same day my car recorded a shade temperature of 26° Celsius. When I watch the weather forecast a predicted shade temperature of anything over 20°C means we are in for a tough day! I guess the worst job when it is hot, is stripping an old roof whilst wearing a dust mask and getting covered in a soot like deposit . . . it makes applying more sun tan lotion difficult.
In contrast this photo from my blog of 29th Jan 2013 shows the other extreme. I would guess if you asked most Thatchers what weather they would prefer to work in, the heat or the cold it would be the cold because you can always add layers but there is very little you can do to combat the heat . . .