NASA Goddard Space Flight Centers Airborne Raman Ozone, Temperature, andAerosol Lidar (AROTEL) measured extremely cold temperatures during all threedeployments (116 December 1999, 1429 January 2000, and 27 February to 15 March2000) of the SAGE III Ozone Loss and Validation Experiment (SOLVE). Temperatureswere significantly below values observed in previous years with large regions regularlybelow 191 K and frequent temperature retrievals yielding values at or below 187 K.Temperatures well below the saturation point of type I polar stratospheric clouds (PSCs)were regularly encountered, but their presence was not well correlated with PSCobservations made by NASA Langley Research Centers aerosol lidar colocated withAROTEL. Temperature measurements by meteorological sondes launched within areastraversed by the DC-8 showed minimum temperatures consistent in time and verticalextent with those derived from AROTEL data. Calculations to establish whether PSCscould exist at measured AROTEL temperatures and observed mixing ratios of nitric acidand water vapor showed large areas favorable to PSC formation but that were lackingPSCs. The flight on 12 December 1999 encountered large regions having temperatures upto 10 K below the NAT saturation temperature but only small, localized regions that mightbe identified as PSCs.