Karachi, African Grey and a pair of cockatiels, and I lost a bird to heat in my first year so I take this seriously.
Humidity is the thing everyone gets wrong here. In Karachi, 38°C at 70% humidity is far more dangerous than 44°C in Multan, because evaporative cooling barely works. Every "cool your bird with misting" tip on the internet was written for a dry climate. On a humid day misting a bird and leaving it in still air makes things worse — you have wet a bird that cannot evaporate. Mist only if there is airflow.
Airflow past, never at. A fan pointed directly at a bird for hours causes exactly the chill people are trying to avoid, and cockatiels in particular go down with respiratory trouble from it. Aim it at a wall a metre away and let the room move.
The wet cloth on one side only — this is in the original post and it is correct, but the reason matters: you are creating a cool side so the bird can choose. Every good heat strategy for a bird is about giving it a gradient to move along. Cover the whole cage and you have removed the choice and the airflow at the same time.
Air coolers. People stand cages in front of them. Do not. A room cooler is fine at the other end of the room; a bird sitting in the direct wet blast is soaked and then chilled, and that is how you get a dead bird on a hot day, which nobody ever believes.
Bathing dish, wide and shallow. Mine bathe twice a day in summer entirely on their own. This is the single most effective thing and it costs nothing.
Watch for: wings held out from the body, open-beak panting, and a bird sitting on the cage floor. That last one is late. A bird on the floor in the heat is an emergency — into shade and moving air immediately, cool (not cold) water on the feet, and a vet.
And the thing that actually killed my bird: the cage was in shade at 9am when I left and in direct sun by 1pm. Shade moves. Check where the sun will be at 2pm, not where it is when you set the cage down.
