Automotive paints and relative humidity. Say wut?

OK so today the temperature is around 90* but the humidity is 25% RH. I have done some research and found that below 40% there can be some issues with the paint not hardening up quick enough due to the lack of moisture combining with the isocyanates in the hardeners.

I stopped in a autobody supply store today in Boise, Idaho and asked the guy behind the counter about low humidity and he was quite helpful. He said they sell a BASF paint and a couple other brands and that 2 of the brands they sell have an additive which can be added to compenste for low relative humidity...Bingo!, I'm not insane. I told him that I had problems with runs and sags on a hot day using the same gun and technique I have used my entire life and he said that you need to spray 2 medium coats for each wet coat you would normally spray. He also said it depended on if you are using a high or low solid clear.

So since I already have my paint purchased I will do my best with what I have. I don't see the humidity going up or the temperature going down for months out here.

Thanks for following this, I used to live in Minnesota and had the high humidity issue...never thought low humidity would be a problem.