I bet it's due to the heat island effect due to the proliferation of roads and parking lots.

All those internal combustion engines filling the congested LA roads aren't exactly cooling the place down either. More of the energy from the fuel is lost to heat out the radiator and tail pipe than goes towards propulsion.

That is something really interesting that I never connected the dots on. Thank you.

That I can see. No shade + concrete is a nightmare. Plus wind is probably limited due to buildings.