In humid time, 13km ownwards, the shoes will start t have squishing sound.
These couple of days, although the temperature is extremely high but the humidity not too bad. I actually felt quite ok for the 15.8km run which I started around 7:30am last night. Shoes and sock are dry. I believe I might have sweated more than usual, but the evaporation of the sweat was fast too. And with my UTO single which stuck to my body, the cooling effect from the evaporation can be felt. so the run wasn't too bad when compare to a humid day.