Global surface temperature, which has already increased approximately 1 °C relative to that in 1850 to 1900, may increase another 2 to 4 °C by the next century. Precipitation in the United States (US), Canada and Europe will mostly increase, while the southwestern US and southern Europe will become drier. These changes are expected to alter the ecology and transmission dynamics of West Nile virus (WNV), the leading mosquito-borne infection in these regions, and Lyme disease and tickborne encephalitis, the respective leading tickborne diseases.