Continuous ozone data obtained at nine sites across southern Louisiana showed that the ozone levels frequently exceeded the federal standard of 80 parts per billion during the three month study period. The days with ozone over the standard were generally characterized as having light winds, abundant sunshine, and high temperatures. Intermittent periods of region wide low ozone were primarily associated with widespread thunderstorm activity. The cold fronts which passed through southern Louisiana during the study period were conducive to nighttime ozone levels which were higher than nighttime levels typically observed during the study period.