Wet air can be compensated for with timing. The biggest thing that will affect a naturally aspirated car is barometric pressure. As actual altitude goes up barometers go down. Also storm fronts can have a great affect on ACTUAL barometer readings. Not what you get on TV weather which is ALWAYS a corrected barometer reading. This is a big factor in calculating DA's. For instance where Brad runs his car the barometer is usually high 29's to over 30. Out here where I am we do back flips if the baro reading reaches 28.00! Why NHRA factors altitiude tracks and changes indexes for the various classes. Those only adjust for the physical altitude not the weather.