According to a recent NASA study Mono Lake and other large lakes in California are warming twice as fast as the local surface air temperature. The data was gathered from 1992 to 2008 using multiple satellites that can track changes in thermal profiles of lakes. The study focused on six large lakes in California and Nevada and looked at night-time lake surface temperature changes from July through September. Mono Lake and Lake Almanor exhibit the greatest upward trend in temperature change.
More information on NASA’s data and a link to the abstract in Geophysical Research Letters can be found here.
The Sacramento Bee has an article with more information and graphics here.