In addition to the above mentioned sources you can also use the following data source:

Iowa Environmental Mesonet (IEM): The IEM maintains an ever growing archive of automated airport weather observations from around the world. (ASOS Network / ASOS-AWOS-METAR Data)

Here is Iowa State University of Science and Technology's website, which offers free download of historical weather data (decoded and METAR):

http://mesonet.agron.iastate.edu/request/download.phtml

With data from this source I was able to produce epw weather files for EnergyPlus.