OP, I'm 4a natural and it works great on my hair. The only time my hair waved up (not totally reverted, just waved up) was when I forgot my umbrella on a stormy day and got caught in heavy rain three separate times.
Other than that, a misty or drizzly day is nothing. My edges do get wavy after a few days, but I also do the thirty splashes method when I wash my face everyday.
Overall, my hair looks like a fresh flatiron until the next time I wash it - no puffiness or frizz. And my hair reverts completely when I shampoo it - no straight sections.