The official DJI maximum operating temp for the M2 - per its specifications - is 104F. I had no issues with the copter/remote at 90F this past summer, but I did have an issue with my iPad overheating in the sun. I then flew from a shaded area, and all was good. The big thing is the copter’s battery. It’s best if it’s cooled to around 60F with direct car AC or otherwise at the start of the flight, and 50% is a good landing time.
I was flying this summer at about 94 degrees about noon and only about 5 minutes into the flight when my camera gimbal on my M2P began to act up. I landed and let things cool a bit and took off again and all was well, but soon it started the same trouble. Again I landed and cooled things down and all was well again.
That has been the only time I have ever had an issue with the drone and the only time I have ever flown in temps. that high. It was not a dry heat but a very humid day too.