I am not sure if there is a direct coralation (and treat this as speculative) but with an increase in heat also comes an increase in "activity". That translates all the way down the food chain including the bacteria. Where there was once a slower more methodical breakdown of nutrient, with increased temps will come increased breakdown increasing the amount of available nutrient to feed unwanted algaes as well as other organisms.
I would think it should be shortlived though. Once the extra nutrient available had been "burned through", things should return to normal.
As I said though, just thinking out loud