For a couple of years I have been collecting soil temperatures in my back yard, I thought it would be interesting to compare surface temperatures as measured by the Terra and Aqua satellites with my observations for 2013. The results are shown in the graph below.
My hole in the ground was located to avoid the mains water supply and be accessible when when crops a growing, this could be described as a random suburban setting. The temperature readings are usually collected around sunset on Sundays. Soil temperature varies considerably during the day and night, the extremes take place when the sky is clear. In summer the noon temperature can reach 30 deg. C, and in winter under a clear night sky, it can fall well below zero. The graph below shows the variation during a spring day. The thermal turbulence is greatest at the surface (measurements taken at 0.1m). The temperature at 1.0m approximates to the average at 0.1m.
The relationship between surface and air temperature is complex, I have yet to investigate this but it seems that the average soil temp approximates to the average air temperature, however the variations in surface soil temperature are greater than those of the air above.