>>2024798September is the nicest time weather-wise in my experience. However, it's borderline in terms of midges... this September was humid, so we got eaten alive--last September was dry, and seriously idyllic. Just take a small thing of repellent and a headnet anyway, takes zero space.
Can corroborate other anon--fire is generally unnecessary (just bring a stove) and not allowed in certain places, water is very good and clean (but having a filter wouldn't hurt for standing water). Some rain gear is good.