Observations and measurements were made of supercooled liquid water in clouds which enveloped high elevation sites in the Colorado Rocky Mountains for the winters of 1980/81 through 1983/84. The observations showed that liquid water was more frequent at the southern and northern Rocky sites than at the central sites. Eighty percent of the liquid water periods persisted 3 to 20 h at the northern Rocky site. This site was enveloped by supercooled liquid cloud 24% of the time during the months of December 1981 and January 1982. Average liquid water contents at the sites ranged between 0.14 to 0.23 g m−3; the maximum individual value was 0.60 g m−3. The measurements indicated that substantial amounts of liquid water were flowing over the Colorado Rockies at mountaintop heights.