Our celebrated streams, lakes, and coasts are fed by an average annual precipitation that ranges from 60 inches in the Catskills to 28 inches in the Lake Champlain Valley. Occasional drought is a normal, recurrent feature of virtually every climate in the United States. Meteorologists and hydrologists have their own precise definitions of drought.
Meteorologists compare deficiencies in precipitation to normal levels when they speak of drought.
Hydrologists consider stream flow and water levels in aquifers, lakes, and reservoirs along with precipitation. New York uses elements of both disciplines to determine when a drought is occurring. New York's Drought Management Task Force uses those factors as well as water use,duration of the dry period, and season to assess drought in different parts of the state. New York also uses the Palmer Drought Index, a measure of soil moisture computed by the National Weather Service. The two indices reveal different aspects of drought.