visibility and meteorological stations were made operational in the Louisiana coastal waters beginning in November 2001. An hourly data record is being archived, and near-real time information is made available over the internet. Simplified formulas are derived for the offshore atmospheric boundary layer which require only easily obtainable input parameters. With these formulations, monthly mean variations of stability, mixing height, and ventilation factor (an indicator of dispersion capability) are provided for the northern Gulf of Mexico. A method for determining whether fog or haze conditions are observed at a monitoring station is given. Using this algorithm, the effects of fog and haze at three coastal stations are discussed. Several periods of reduced visibility at our primary monitoring station are examined using pertinent weather maps and satellite observations. It is shown that naturally occurring fog conditions are by far the most common cause of reduced visibility along the Louisiana coast. Haze can be observed each month; however, the total duration is small and the extent to which it reduces visibility is usually much less than that due to fog. Plumes from inland (near-coast) areas can affect the OCS region.