The world number two has sometimes struggled in hot and humid conditions, most notably when severe cramp nearly forced him to quit his Australian Open third-round match in January and when he retired in Shanghai last year.
However, he showed little sign of discomfort during his 7-6(6) 7-6(4) win over Daniil Medvedev on Sunday, when the temperature approached 35 degrees Celsius shortly before the final's scheduled start time of 2 p.m.
"It was hot but it wasn't humid, so it makes a difference," Sinner told reporters.
"But I've been here a week before the tournament started. Very similar conditions as it was today. We put in long days of practice. I felt very well prepared, so I wasn't having issues with the weather and the heat, which is very positive for me.
"It's all part of the process we're trying to do and becoming the best possible athlete. We definitely do a lot of work in the gym to play at this level."
Victory meant Sinner has now collected titles at all six ATP Masters 1000 events on hardcourts, as well as the ATP Finals, Australian Open and US Open on the surface, to join an elite group also comprising Roger Federer and Novak Djokovic.
"I knew that this was a tournament I haven't won, so I wanted to prepare in the best possible way, as professionally as possible," he said.
"Having this achievement now means a lot to me. Now I have couple of days to relax ... there is not so much time in between here and Miami.
"It's again an important tournament in Miami, but we try to play the best tennis possible there too."