(Put this map on your website)
WorldClim (Hijmans et al., 2005) presents the interpolated climate surfaces for global land areas (excluding Antarctica) at very high spatial resolutions of 30 arc-seconds, 2.5 arc-minutes, 5 arc-minutes, and 10 arc-minutes. Above tool visualizes the data retrieved from the 5 arc-minutes (~10 km spatial resolution) dataset. Based on the historic and future climate data from a variety of sources, authors of WorldClim improved the spatial resolution using an interpolation method, called the thin-plate smoothing spline algorithm, with latitude, longitude, and elevation as independent variables. See http://WorldClim.org for more information about the methodology and data download.
Hijmans, R.J., S.E. Cameron, J.L. Parra, P.G. Jones and A. Jarvis, 2005. Very high resolution interpolated climate surfaces for global land areas. International Journal of Climatology 25: 1965-1978