Fog Information at the Airport Sites
The airport sites conveniently show the three weather elements (temperature, dewpoint and relative humidity) for the last hour that are needed for estimating the likelihood of fog. See: Estimating the Likelihood of Fog on the River. The Summary section might also contain notes about fog in the “Weather” column of the hourly data.
There is not a close connection between the presence of fog at the airports and fog on the ARC stretch of river. Because local conditions on the river are often highly conducive to fog, there might be fog on the river in many cases when there is none at the airports. This is particularly true on clear mornings when the fog will likely burn off at the airports before it burns off on the river. Notwithstanding this, it is a good bet that if one or both of these airports are reporting fog, the chances of there being fog on the river are higher as well.