[jrockway]

My understanding is that the FAA sites aren't as useful as they could be for weather forecasting. Apparently many sites are too close to the ground, so the temperature data and dewpoint data is unusable for mesoscale analysis. Sometimes the dewpoint is above the air temperature, for example, which is impossible. It doesn't really matter for air traffic, but it does matter for forecasting storms.

If you are interested in the wind direction or the height of the cloud bases, the aviation weather stations are OK. If you are interested in temperature data, you will have to look elsewhere. (Many states have observation sites designed for weather purposes. The Oklahoma Mesonet was the first, but other states have them too. Often these sites have very interesting information, like soil moisture and temperature, and temperatures at varying heights above the ground: http://www.nysmesonet.org/about/sensors http://www.mesonet.org/index.php/site/about/instruments)

[RNCTX]

Don't know where this criticism comes from but temp and dewpoint data absolutely matter for air traffic, because it determines cloud bases. If cloud bases are below the decision height for the instrument approaches into an airport, it's illegal for a commercial operator to depart from there (because they could not reliably return to the field in case of emergency after takeoff).

The standard data output of an FAA weather station is in degrees Celsius, however, there is no accuracy more than that.

[jrockway]

They measure cloud bases directly, with a laser-based sensor.