Heat and humidity didn't change. The heat that had been building up from the lava fields had drifted over to the grassy fields due to the heavy misty cover from the rain. This left the entire area, regardless of lava with this hot temperature.
However, it was the grassy fields that had suffered more. It didn't have the heat of lava to force some of the heavy mist away. Instead, it just built up making it feel like the group was swimming through the air. Even when Clark had directed the wind with the flowing storms meditation technique to remove the mixed in smoke.
"If anyone else had not been affected by the hallucinogenic smoke, then they might have gotten rid of it by now. That means that the blood moon cultists here might have the city in lockdown. And not just for a short time." Clark saw the others behind him ready to fight.
