Abstract
The relationship between weather and influenza and pneumonia mortality was examined retrospectively using daily data from 1980 to 2009 in Auckland, New Zealand, a humid, subtropical location. Mortality events, defined when mortality exceeded 095 standard deviation above the mean, followed periods of anomalously cold air (t(a.m.) = -41, P < 001; t(p.m.) = -42, P < 001) and/or anomalously dry air (t(a.m.) = -41, P < 001; t(p.m.) = -38, P < 001) by up to 19 days. These results suggest that respiratory infection is enhanced during unusually cold conditions and during conditions with unusually low humidity, even in a subtropical location where humidity is typically high.