metpy.plots.StationPlot and metpy.plots.scattertext example and use cases produce "ValueError: not enough values to unpack (expected 4, got 3)"

[wjcapehart]

What went wrong?

In both the older "metpy.plots.StationPlot" and newer "metpy.plots.scattertext" in which the example gallery for plotting fronts (and my own implementation) provides a "ValueError: not enough values to unpack (expected 4, got 3)"

When running the example IPython notebook (and also in our own realtime implementation)

The example below shows Unidata MetPy's own example:

https://unidata.github.io/MetPy/latest/examples/plots/Plotting_Surface_Analysis.html

Jupyter Notebooks and HTML of notebooks are attached here (with documentation on all associated libraries and their versions for the error I am getting on my MacBook).
Plotting_Surface_Analysis_METPY_1p7.ipynb
Plotting_Surface_Analysis_METPY_1p7.html

The error was first noticed circa mid-August 2026 with MetPy 1.6 (in code using StationPlot) and then 1.7.1 (for both StationPlot and scattertext)

The traceback errors do not go as far back into the call to scattertext or StationPlot. Error occurs in both MacOS and Ubuntu 22.04 LTS

Operating System

MacOS

Version

1.7.1

Python Version

3.13.15 64bit [Clang 19.1.7 ]

Code to Reproduce

See code from Example Gallery for Plotting Fronts:

https://unidata.github.io/MetPy/latest/examples/plots/Plotting_Surface_Analysis.html

I also attached an IPYNB and the HTML download of the IPYNB.

Error will emerge with either line example below:

        scattertext(ax, x, y, field[0],
                    **complete_style[field], transform=ccrs.PlateCarree(), clip_on=True)
        scattertext(ax, x, y, rows.strength, formatter='.0f', loc=(0, -10),
                    **complete_style[field], transform=ccrs.PlateCarree(), clip_on=True)

(Also occurs with earlier StationPlot examples from previous versions of the same tutorial example.

Note that the traceback error does NOT back track into the example source code.

Errors, Traceback, and Logs

---------------------------------------------------------------------------
ValueError                                Traceback (most recent call last)
File ~/miniforge3/lib/python3.13/site-packages/matplotlib/backend_bases.py:2257, in FigureCanvasBase.print_figure(self, filename, dpi, facecolor, edgecolor, orientation, format, bbox_inches, pad_inches, bbox_extra_artists, backend, **kwargs)
   2254     # we do this instead of `self.figure.draw_without_rendering`
   2255     # so that we can inject the orientation
   2256     with getattr(renderer, "_draw_disabled", nullcontext)():
-> 2257         self.figure.draw(renderer)
   2258 else:
   2259     renderer = None

File ~/miniforge3/lib/python3.13/site-packages/matplotlib/artist.py:94, in _finalize_rasterization.<locals>.draw_wrapper(artist, renderer, *args, **kwargs)
     92 @wraps(draw)
     93 def draw_wrapper(artist, renderer, *args, **kwargs):
---> 94     result = draw(artist, renderer, *args, **kwargs)
     95     if renderer._rasterizing:
     96         renderer.stop_rasterizing()

File ~/miniforge3/lib/python3.13/site-packages/matplotlib/artist.py:71, in allow_rasterization.<locals>.draw_wrapper(artist, renderer)
     68     if artist.get_agg_filter() is not None:
     69         renderer.start_filter()
---> 71     return draw(artist, renderer)
     72 finally:
     73     if artist.get_agg_filter() is not None:

File ~/miniforge3/lib/python3.13/site-packages/matplotlib/figure.py:3282, in Figure.draw(self, renderer)
   3279             # ValueError can occur when resizing a window.
   3281     self.patch.draw(renderer)
-> 3282     mimage._draw_list_compositing_images(
   3283         renderer, self, artists, self.suppressComposite)
   3285     renderer.close_group('figure')
   3286 finally:

File ~/miniforge3/lib/python3.13/site-packages/matplotlib/image.py:133, in _draw_list_compositing_images(renderer, parent, artists, suppress_composite)
    131 if not_composite or not has_images:
    132     for a in artists:
--> 133         a.draw(renderer)
    134 else:
    135     # Composite any adjacent images together
    136     image_group = []

File ~/miniforge3/lib/python3.13/site-packages/matplotlib/artist.py:71, in allow_rasterization.<locals>.draw_wrapper(artist, renderer)
     68     if artist.get_agg_filter() is not None:
     69         renderer.start_filter()
---> 71     return draw(artist, renderer)
     72 finally:
     73     if artist.get_agg_filter() is not None:

File ~/miniforge3/lib/python3.13/site-packages/cartopy/mpl/geoaxes.py:509, in GeoAxes.draw(self, renderer, **kwargs)
    504         self.imshow(img, extent=extent, origin=origin,
    505                     transform=factory.crs, *factory_args[1:],
    506                     **factory_kwargs)
    507 self._done_img_factory = True
--> 509 return super().draw(renderer=renderer, **kwargs)

File ~/miniforge3/lib/python3.13/site-packages/matplotlib/artist.py:71, in allow_rasterization.<locals>.draw_wrapper(artist, renderer)
     68     if artist.get_agg_filter() is not None:
     69         renderer.start_filter()
---> 71     return draw(artist, renderer)
     72 finally:
     73     if artist.get_agg_filter() is not None:

File ~/miniforge3/lib/python3.13/site-packages/matplotlib/axes/_base.py:3367, in _AxesBase.draw(self, renderer)
   3364 if artists_rasterized:
   3365     _draw_rasterized(self.get_figure(root=True), artists_rasterized, renderer)
-> 3367 mimage._draw_list_compositing_images(
   3368     renderer, self, artists, self.get_figure(root=True).suppressComposite)
   3370 renderer.close_group('axes')
   3371 self.stale = False

File ~/miniforge3/lib/python3.13/site-packages/matplotlib/image.py:133, in _draw_list_compositing_images(renderer, parent, artists, suppress_composite)
    131 if not_composite or not has_images:
    132     for a in artists:
--> 133         a.draw(renderer)
    134 else:
    135     # Composite any adjacent images together
    136     image_group = []

File ~/miniforge3/lib/python3.13/site-packages/matplotlib/artist.py:71, in allow_rasterization.<locals>.draw_wrapper(artist, renderer)
     68     if artist.get_agg_filter() is not None:
     69         renderer.start_filter()
---> 71     return draw(artist, renderer)
     72 finally:
     73     if artist.get_agg_filter() is not None:

File ~/miniforge3/lib/python3.13/site-packages/metpy/plots/text.py:233, in TextCollection.draw(self, renderer)
    230 _, info, _ = self._get_layout(renderer)
    231 self._text = ''
--> 233 for line, _, x, y in info:
    235     mtext = self if len(info) == 1 else None
    236     x = x + posx

ValueError: not enough values to unpack (expected 4, got 3)

[dopplershift]

This is caused by Matplotlib 3.11 and will be fixed in #4076 .