The Automated Surface Observation System, also known as ASOS, is a joint partnership between the National Weather Service (NWS), the Federal Aviation Administration (FAA) and the Department of Defense (DOD). The ASOS system serves as the nation’s primary surface weather observing network.

There are a total of 900 sites across the country, three of which are here in North Alabama. These are located at the Huntsville International Airport, the Decatur Airport and the Muscle Shoals Airport. The system transmits one-minute, five-minute and one-hour observations.


The weather sensors associated with the ASOS report to another processor on the opposite side of the airfield. From there, the data is transmitted over phone lines through various locations. Both the FAA and the NWS receive one-minute observations, while the public receives the five-minute and hourly data.

This technology is important because it helps protect both life and property. Receiving accurate information about the atmosphere frequently is the key to improving forecasts and warnings. When it comes to the FAA, weather conditions can threaten aviation safety. Aviation parameters that are crucial for flights are accurately measured at an ASOS site.

Break Down Of The ASOS

NWS Electronic Technicians Christopher Bryant and Bradley Smith explain each instrument of the ASOS

The ASOS site at the Huntsville International Airport has been operational since the early 1990s. Since the late 1940s, most climate observing sites were located at airports where staff took meteorological measurements. Throughout the years, similar to Huntsville’s airport, many of the locations have changed. To maintain a long history of observations, ASOS data is used in conjunction with human observations to continue climate data.

The site consists of multiple instruments that measure different environmental parameters. Some of these include temperature, dew point, wind speed, wind direction and visibility. For even more information on the ASOS, you can go to