EX-P is one of my "go to" favorite products. I really like my results with it. I've used it when the temperatures were in the mid 40's on a sunny clear day with no problem. I've also used when the temperatures were in the low 50's but the sky was over cast and it was damp (it had been raining but had let up). I had problem removing the product (smeared) and I had clouding on the finish that popped up during the next week. The clouding wiped off easily but really made me feel like I hadn't wiped the product off when I used it.
I live in a very dry climate so I can't say how EX-P does in a real humid climate but it didn't seem to like cool humidity. This wouldn't begin to change my opinion of the product but I now know I would apply EX-P in a heated garage on cool, damp days.