The Coastal-Marine Automated Network (C-MAN) was established by NDBC for the NWS in the early 1980's. The development of C-MAN was in response to a need to maintain meteorological observations in U. ... S. coastal areas. Such observations, which had been made previously by USCG personnel, would have been lost as many USCG navigational aids were automated under the Lighthouse Automation and Modernization Program (LAMPS). In all, approximately 60 stations make up C-MAN.
C-MAN stations have been installed on lighthouses, at capes and beaches, on near shore islands, and on offshore platforms (see the NDBC station location map for all station locations).
C-MAN station data typically include barometric pressure, wind direction, speed and gust, and air temperature; however, some C-MAN stations are designed to also measure sea water temperature, water level, waves, relative humidity, precipitation, and visibility. These data are processed and transmitted hourly to users in a manner almost identical to moored buoy data. In addition to the conventional method of data transmission, certain C-MAN stations are equipped with telephone modems that allow more frequent data acquisition, data quality checking, and remote payload reconfiguration or restarting.
More info at http://www.ndbc.noaa.gov/cman.phtml