Meteorological conditions associated with increased incidence of West Nile virus disease in the United States, 2004-2012

Above average annual temperature was associated with increased likelihood of higher than normal WNV disease incidence, nationally and in most regions. Lower than average annual total precipitation was associated with higher disease incidence in the eastern United States, but the opposite was true in most western regions. Although multiple factors influence WNV transmission, these findings show that anomalies in temperature and precipitation are associated with above average WNV disease incidence.

Readily accessible meteorological data may be used predictive models to forecast geographic areas with elevated WNV disease risk before the coming season.