In this study, the LST MODIS product (v006, level 3) which provides the daytime and nighttime land surface temperature was used to evaluate the space-temporal variation of the water surface temperature (LWST) of Lake Titicaca, during the period 2000–2020. The Mann-Kendall tests and the Sen's method were applied to determine the statistical significance and the rates of change of the maximum air and water temperatures. The results show that the average annual LWST cycles of Lake Titicaca fluctuate between 12.3°C (August) and 13.8°C (April) in region A (Major Lake), and between 10.6°C (July) and 14.8°C (November) in region B (Minor Lake). In addition, there is a general increasing trend of the average LWST during the coldest time (winter) of the year, with more intense warming effects in some shallow areas and in coastal areas. In Major Lake, the significant increasing trend of daytime and nighttime LWST was maintained at a rate of 0.30 [0.14, 0.40]°C/decade and 0.34 [0.18, 0.45]°C/decade respectively. Also, the maximum local air temperature trend during the austral winter (JJA) shows a significant increasing trend of 0.52 [0.16, 0.87]°C/decade between 1983 and 2013. This fact could be responsible for the change in trend in the surface temperature of Lake Titicaca.