Humidity and Weather
Recall that 100% rH means that the air is saturated. If additional moisture is added, or the temperature drops, that water vapor must condense and fall to the surface of the Earth as precipitation. Because of this, forecasters use rH values to predict where there is a potential for precipitation to form. If the rH values are low, there is a low chance that precipitation will form.
*rH values do not need to be 100% at the surface for precipitation. But the atmosphere must be saturated at most levels to allow requisite cloud formation for precipitation.