Thes best data centre to dawnload world climatic data

Summary of the Day by NOAA: 

http://www.ncdc.noaa.gov/cgi-bin/res40.pl?page=climvisgsod.html

https://climatedataguide.ucar.edu/

http://drinet.hubzero.org/

International Research Institute for Climate & Society Data library:

http://iridl.ldeo.columbia.edu

CRU: 

http://www.cgiar-csi.org/data/uea-cru-ts-v3-10-01-historic-climate-database

http://www.drias-climat.fr/

http://freezethaw.ntsg.umt.edu (go to data holdings) 

http://nsidc.org/data/nsidc-0477

WorldClim Database:

www.worldclim.org/ 

http://www.geoportal.org The best starting point would be GEO and its portal for GEOSS - Global Earth Observation System of System where you will be able to find climate data from a number of data centres.