Webber charcoal struggling to get above 300F in high humidity.

I'm from central CA and am visiting family in Pennsylvania. I'm bbqing for them on the same grill but new, and I can't get it above 300. It's super humid here above 80%, and back home it's usually less than30%. Is the humidity why it won't get as hot? The air is also just sitting, not sure if it's allowing enough ventilation. Ideas?