  It was all known that Lhasa went through a high temperature of
30.8$^{\circ}$C in late June 2019, which hit record highs. To better understand
the reasons, based on observations recorded at automatic weather stations in
Lhasa, we studied the characteristics of temperature variation at multiple time
scales using the linear trend method, Mann-Kendall mutation test, morlet
wavelet analysis, R/S analysis and so on. The results showed that: (a) The
annual mean temperature (AMT) is rising at a rate of 0.5$^{\circ}$C/10yr, and
the average temperature for different seasons also increased significantly,
especially in winter. (b) Although there was an intersection in 1995, we found
that AMT, did not pass the reliability test of significance level ${\alpha}$
=0.05, this means there are no abrupt changes for AMT, the values are
7.97$^{\circ}$C and 9.15$^{\circ}$C respectively before and after the
intersection point. (c) AMT has a periodic oscillation for 18~25yr and 25~32yr
based on a mass of data and the wavelet variance diagrams in Lhasa. AMT has a
main cycle of 28yr, cyclic Patterns of temperature changes in spring, summer
and autumn is similar to AMT, but it is relatively complex in winter. (d) The
Hurst index of AMT and different seasons demonstrates that the temperature are
likely to continue to rise in the future in Lhasa.
