Cloengaa

Hey all, I thought about space travel in the future. As I understand it then different gasclouds in space are very very hot. As we travel between earth and the moon or Mars we do not pass these clouds, but say in the future when travel becomes more extensive and we can travel in the universe. Would we not have to avoid such clouds ? I mean a cloud consists of matter and I take it the spacecraft would feel the intense heat in the clouds or am I totally wrong ? Chris