Are air temperatures the same over land and water?

Air Temperature Graph
Map of Station CLKN7

This graph shows the average monthly air temperatures from land station CLKN7 (Cape Lookout, NC) and deep-ocean buoy station 41001. These two stations are just about on the same latitude -- about 34.6 degrees North latitude. They are only 192 miles apart!! You would think that the air temperatures would be very similar to each other. But as you can see from the graph, the air temperatures for the Winter months of November (month 11) through March (month 3) differ substantially. For example, the average January (month 1) air temperature measured at land station CLKN7 is about 8 degrees Celsius while the average January air temperature at deep-ocean station 41001 is 15 degees. This is a difference of 7 degrees!!

What do you think causes this difference in air temperatures between two stations that are only 192 miles apart?