Anomalously high radiances from the ozone channel of the Limb Infra‐red Monitor of the Statosphere (LIMS) sounding instrument have been observed in the Northern Hemisphere winter lower stratosphere. Such events, thought to be due to polar stratospheric clouds (PSCs) are examined further by computing relative humidities using Stratospheric Sounding Unit (SSU) temperatures and water vapour measurements from the LIMS Map Archive Tape (MAT) analyses. Regions identified as PSCs are found to correspond closely to regions of high humidity. While instances of saturation were found, the average humidity at the centres of 39 PSCs was calculated to be 58%. Possible reasons for this apparent discrepancy are discussed.Applying a similar approach to the Southern Hemisphere, in 1979, virtually no PSCs are found in the vortex after 10 September at 20 km. This result has important implications for a number of proposed explanations for the Antarctic ozone hol