When is the best time to run?
The answer is more simple than you think!
When I run or recommend running depends on the type of run and the time of the year.
For easy runs:
During the warmer months, doing easy runs in the heat of the day (considering your safety, of course) may stimulate some heat adaptation which could be beneficial. Learn more about heat adaptation here. The pace of these runs is unimportant as long as it’s easy.
For hard / long runs:
During the warmer months I’ll often do these asap in the morning to avoid the heat. During the colder months here in South Dakota I’ll often do harder / longer runs when the temperature is warmer in the afternoon. Running hard in the morning also gives me plenty of time to do an easy afternoon/evening double run.