TUCSON, AZ (Tucson News Now) - Warm, moist tropical air is needed for monsoon storms to get going over southern Arizona.
That is why we track the dew point numbers very closely from June to September.
When dew points are below 50 degrees, the air is generally too dry for widespread downpours. When dew points are at or above 54 and conditions are favorable in the atmosphere for storm development, storms can form and produce heavy rains.
Dew points are the temperature at which the water vapor in the air condenses into liquid water.
A high relative humidity indicates the dew point is closer to the current air temperature.
Relative humidity of 100 percent indicates the dew point is equal to the current temperature and that the air is completely saturated with water.