Temperature, dew point temperature, and air mass frequencies were examined 17 days prior to and throughout each of the 12 high P&I mortality episodes identified from 1975-2002. There is a statistically significant negative relationship between episode duration and mean 1200 UTC dew point (r = 20.61, p,0.05; Figure 3a ). The longest episode (57 days in 1981) was associated with a dry period during which the mean dew point was more than 0.8uC below normal for that time of year. Total episode mortality is likewise negatively correlated with 1200 UTC dew point (r = 20.56, p,0.05; Figure 3b ). Two of the three episodes with the lowest mortality also had dew points that were near normal, whereas the higher mortality episodes exhibited drier conditions. No significant relationships were found for afternoon variables, air temperature, or any of the SSC air mass types.