You could have the moods of the city be reflected by the weather pattern. Like if its feeling vengeful, or angry, or something, there could be lightning, or if its feeling mysterious, fog. And then you could have encounters for the players based on those weather patterns. Like in the lightning one, you could have some flaming balrog thing attack, or some other monster or event that reflects the mood. Like have it be sunny and then give the players a helpful occurrence.
And you could work in the bad mood weathers into the cultures and traditions of the tribe. Like each tribe is scared of lightning, only with a good reason. And then the players could see if Hellgate particularly likes them or not, based on their weather. And then you could be justified in giving each PC their own personal rain cloud! ("It's not me that hates you, it's Hellgate!")
Has this advice arrived too late? Have the PCs hit Hellgate yet? And if they have, did the die?