With PyCharm 5.0 we finally got to select Google and NumPy Style Python Docstrings templates.

It is also mentioned in the whatsnew section for PyCharm 5.0.

How to change the Docstring Format:

File --> Settings --> Tools --> Python Integrated Tools

There you can choose from the available Docstrings formats:

Plain, Epytext, reStructuredText, NumPy, Google

As pointed out by jstol: for Mac users, this is under

PyCharm -> Preferences -> Tools -> Python Integrated Tools.

Not sure why it doesn't default to loading the local module docstring in this case. However you can load external docs inline by adding patterns to PyCharm to tell it where to find external documentation for a given module.

1. Go to Settings > Tools > Python External Documentation
2. Click Add (+) Button to add a new module to the list
3. Set module name: numpy, URL/Path Pattern: https://docs.scipy.org/doc/numpy/reference/generated/{element.qname}.html
4. Click Ok and Apply
5. Now when you look up numpy docs you get everything inline

You can adjust this by going to the Python Integrated Tools settings.

On Windows/Linux

File -> Settings -> Tools -> Python Integrated Tools 

On OS X

PyCharm -> Preferences -> Tools -> Python Integrated Tools

Then there is a Docstrings section. Change the drop down format to NumPy and press "OK"