Three case studies of one to two days duration have been chosen from a three-month data set (July 17 to October 17, 1976) to provide a detailed investigation of the relationship of weather events - especially transport - to the distribution of ozone in southern Louisiana. The results of these case studies indicate that heavy local emissions of ozone precursors in the Baton Rouge area cause a pronounced increase in the ozone levels at nearby sites downwind, and a lesser, but noticeable increase of ozone at sites up to about 45 miles downwind, with abundant sunshine. Similar effects of precursor sources in the New Orleans area could not be determined except for long distance (about 30 miles) downwind because of unfavorable prevailing winds. Ventilation appears to regulate the intensity of the ozone increase, with poor ventilation favoring high ozone and good ventilation favoring lower ozone. Also, large shower areas with heavy cloud cover were observed to be associated with low ozone levels. Finally, two sites near the coast showed a slower than normal decline from high ozone levels when the air with high ozone had arrived from offshore.