A sample of daily precipitation and temperature data from 30 weather-observing locations in or near the Upper Colorado River Basin have been placed on cards and partially analyzed by computer techniques. The sample represents a total of 1660 station years and analytical conclusions give a good representation of the climatic ranges for this area. Frequency of precipitation at multiple time intervals for each location are presented. Major storms having a recurrence less than once per year have been found to contribute significantly to runoff in the Upper Colorado River. Preliminary techniques for adjusting actual precipitation to more closely relate to runoff are presented and further refinements are anticipated. Variations in moisture sources have been studied.