For hair and makeup done for an outdoor event in humid weather, the technique and amount of product used is genuinely different than for an indoor event with AC, or even a cooler outdoor one. The goal is always for it to last the whole event, especially for photos — and humidity is one of the biggest factors we plan around.
Hair and makeup technique and product depend mostly on your hair and skin texture, the style or look you're going for, and the weather. In humid conditions, that usually means more hair product and volume up front, and a few extra layers of makeup at the start.
Think of it as a protective layer between you and the sauna-like heat — one that will settle and blend into your skin and hair naturally as the day goes on.