I drink coffee most days and prefer it to be hot ,not warm or lukewarm, if it's not too my liking then I send it back and tell them it's not hot enough. Of course it does help if you can speak some Thai to emphasize your point.
In my experience many coffee places here serve warm tepid coffee, I've made myself a regular at a couple of places where the coffee is nearly always served piping hot so I tend to only use those places.