Having spent some time in Phnom Penh over the past month, it seemed to me that the Cambodian city was much more hot and glaring than Bangkok. So today back in BKK I checked this by compiling one of my favorite indexes for the two cities: Extreme Cooling Degree Days (CDD29). This was derived from the excellent web site degreedays.net which allows you to calculate cooling degree days based on any temperature base you like. In this case I used a base of 29C (84F) which is the maximum allowable temperature for comfortable (sweat-free) sleeping IMHO.Cambodian expats escribe PP as insufferable in the hot season (April-May) and the above graph suggests it is a little but not much worse than Bangkok at that critical time of year.
On the other hand PP has many fewer high-rise buildings than BKK, and the shading seems to me much less there, the sun penetrating down to street level. A more accurate comparison would require a careful comparison of downtown urban microclimates, and also, I conclude, consideration of the degree that uncomfortable glare aggravates the subjective sense of thermal discomfort.
