According to Cit Var of the World, "in Isreal the best quality Shamouti is produced in the narrow coastal belt, and on Palestine Sweet Lime rootstock"
Also, "It's productvity and external and internal fruit quality are greatly affected by climatic conditions, rootstock and soil factors."
So it would seem it may not like heat as much as one would expect, coming from the Middle East. Perhaps your climate has some moderating factor such as hot days/cold nights, but it would be interesting to find out specifically what the quality loss in hot areas is exactly, and if it is still ok for home production, rather than commercial production as quoted.