I monitor my grow vault meticulously, and as long as the lamp is on and the fans are blowing the humidity stays around 50 percent. that might be different in a bigger grow area (mine is like 4'2'3' so my sodium light cooks out all the unwanted moisture). But no matter what the humidity is outside, you can regulate your grow conditions with ventilation and lamps, just check the stats regularly to avoid mold. As for the flowering phase, let the plants be alone in darkness, without the moisture of other plants' media discombobulating flowering. If the weather is especially humid, try a paper bag over the plant during its dark period with a hit of CO2 (which can be produced by mixing vinegar and baking soda in a 2-liter bottle. expel the gas into a balloon, then release it underneath the paper bag for the plant to enjoy). You might want to do a search to get exact parts of baking soda and vinegar. This will at least let the plant breath easier while it's away from the light. This should only be a last resort if regular ventilation doesn't relieve humidity during the dark period