Surfaces with lower specific heat capacities tend to be hotter on a hot day and colder on a cold day.
The specific heat capacity of an object is the amount of heat required to raise the temperature of a unit mass by one unit temperature (usually degC or K).
Surfaces with higher heat capacities such as water will require a greater amount of heat to get to a certain temperature than those with lower heat capacities such as concrete.
Given the same amount of insolation from the sun on a hot day, concrete surfaces tend to be hotter because it is at a higher temperature while water will have a lower temperature. This is because a unit mass of concrete only requires a small amount of heat to raise its temperature by one degree but a unit mass of water will need a significantly larger amount of heat to raise the temperature by the same degree.
Thus, concrete roads in a town will have a larger variation or more extreme temperatures while places near a water body will experience a much lower temperature range.