This site is a mirror of the IANA (Olson) timezone database files, with python-dateutil accessible data and metadata.
The main site for these data files can be found at the IANA's website. The archive of releases is here (FTP). More information can be found at the code repository. I have verified that all files from version 2012j-2016e have been signed using key ID 0x62AA7E34. The built zoneinfo files are signed with my own key, 0xD964BEFB.
Note: I have not yet verified the new key used to sign the 2016f release, and have only verified the sha512 checksum. Proceed with due caution. The change in GPG key was, however, mentioned in the announcement of the 2016f release, so there is no particular reason for suspicion.
To use these files with dateutil, run updatezinfo.py with the appropriate arguments to build the zoneinfo database - this requires zic. For convenience, a zoneinfo metadata file is provided alongside each release, which can be used as an input to updatezinfo.py. Additionally, prebuilt zoneinfo files are provided for each release, and can be placed directly in your dateutil/zoneinfo file (it must be named dateutil-zoneinfo.tar.gz).