Selin Co Lake is expanding at a rate of 20% or an average of 420 km² per decade. Thus, it has become the largest inland salty lake in Tibet, exceeding the area of Nam Co Lake during 1999-2008. The main reasons for the lake's expansion are the increase in snow/ice meltwater under the backdrop of global warming, an increase in precipitation, decrease of evaporation, and degradation of the permafrost. However, variations and trends in extreme climate events are more sensitive to climate change than are mean values and thus, they have received greater attention. In this study, a trend analysis was performed to identify the change regulation of extreme weather conditions in the Selin Co basin, based on a meteorological data set of daily maximum, minimum, and average temperatures from 1961-2012 obtained at two weather stations. The methods of a 10-year smoothing average, linear regression, correlation analysis, and a Mann-Kendall test were employed to delineate the rate of change, abrupt change points, statistical significance of the trends, and periodicities of extreme temperature indices. The results show both the maximum daily maximum temperature and the minimum daily minimum temperature (TNn) exhibit an increasing trend over the study period, especially for TNn, which has the higher value of 1.10 ℃/10a. Extreme warm indices such as the minimum daily maximum temperature, percentage of days when the maximum temperature >90th percentile (TX90p), and percentage of days when the minimum temperature >90th percentile (TN90p), together with the growing season length (GSL), showed marked rates of increase of 0.24 ℃/10a, and 5.63, 10.0, 2.31 d/10a, respectively. However, the extreme cold indices such as the number of frost days, ice days, percentage of days when the maximum temperature <10th percentile (TX10p), percentage of days when the minimum temperature <10th percentile (TN10p), and diurnal temperature range (DTR) showed significant rates of decrease of -4.47, -5.63, -5.23, -11.20 d/10a, and -0.28 ℃/10a. Most of the range in the variation of extreme cold temperature indices in the basin is higher than that on a global, national, and Tibetan scale, especially for TN90p, which has the maximum magnitude of variation. On a decadal scale, the indices of TNn, TX90p, TN90p, and DTR increased, whereas the extreme cold indices and GSL decreased. Abrupt change analysis indicates that abrupt points can be found in each extreme cold index, occurring mainly after the mid-1980s. Expansion of the Selin Co Lake area is assumed to be related to the significant increase of minimum temperature. The corresponding extreme cold indices, TX10p and TN10p, are correlated negatively with the change in the Selin Co Lake area, whereas the TN90p and the annual mean temperature are correlated positively. The rise of the extreme warm indices and fall of the cold indices illustrate clearly that the climate is warming, which accelerates the retreat of valley glaciers, and the snow meltwater feeds the lake's expansion.