Siphon is a collection of Python utilities for downloading data from remote data services. Much of Siphon’s current functionality focuses on access to data hosted on a THREDDS Data Server. It also provides clients to a variety of simple web services.

Siphon follows semantic versioning in its version number. With our current 0.x version, that implies that Siphon’s APIs (application programming interfaces) are still evolving (we won’t break things just for fun, but many things are still changing as we work through design issues). Also, for a version 0.x.y, we change x when we release new features, and y when we make a release with only bug fixes.

We support Python >= 3.5 and currently support Python 2.7.


We are dropping support for Python 2.7 in the Fall of 2019. For more details and rationale behind this decision, see Python 2.7 Support.

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Other Resources

  • Unidata’s Python gallery contains many examples using Siphon to access remote data
  • The materials for Unidata’s annual Python training workshop includes some tutorials on using Siphon.


Siphon is available under the terms of the open source BSD 3-Clause license.