This paper will summarize the key weather features observed during the July 2002 North East Oxidant and Particle Study (NEOPS) Intensive Observing Period (IOP). Several episodes of enhanced concentrations of ozone and fine particles were observed during this IOP and will be examined in more detail with respect to synoptic and mesoscale phenomena associated with these episodes. In particular, an intense smoke and haze event occurred on July 7-9 associated with wildfires in northern Quebec. This episode was characterized by unusually high concentrations of fine particulate matter and localized areas of high ozone concentrations as well.