Bug summary

1. Date formatting usingstrftime format codes should use thecurrent locale's names. While this works as expected on Linux,ConciseDateFormatter by default shows English month names etc. when running on a non-English locale. It only works correctly after explicitly setting the locale to the current one bylocale.setlocale(locale.LC_ALL, '').

2. Settingaxes.formatter.use_locale toTrue doesn't have any effect on Windows unless you explicitly set the locale to the current one bylocale.setlocale(locale.LC_ALL, '') (again, it works correctly on Linux). I don't understand why this is so as__init__ does exactly the same thing but for some reason without effect on Windows:
   

   matplotlib/lib/matplotlib/__init__.py

   Lines 972 to 973 inf5ff5d7

   	ifrcParams['axes.formatter.use_locale']:
   	locale.setlocale(locale.LC_ALL,'')

Code for reproduction

importlocaleimportplatformimportmatplotlibasmplimportmatplotlib.pyplotaspltimportnumpyasnpdates=np.arange(np.datetime64('2022-12-01'),np.datetime64('2022-12-02'),np.timedelta64(1,'h'))values=np.zeros_like(dates,dtype=int)defplot(title):fig,ax=plt.subplots(figsize=(6,1.5),layout='constrained')ax.plot(dates,values,'white')ax.xaxis.set_major_formatter(mpl.dates.ConciseDateFormatter(mpl.dates.AutoDateLocator()))ax.text(.5,.5,f"{locale.getlocale()=}\n{ax.yaxis.get_major_formatter().get_useLocale()=}\n({platform.system()})",transform=ax.transAxes,ha='center',va='center')ax.set_title(title)fig.savefig(title+'.png')# use \N{MODIFIER LETTER COLON} instead of regular colon for Windows file namesplot('1꞉ default')withmpl.rc_context({'axes.formatter.use_locale':True}):plot('2꞉ axes.formatter.use_locale = True')locale.setlocale(locale.LC_ALL,'')plot("3꞉ setlocale(locale.LC_ALL, '')")withmpl.rc_context({'axes.formatter.use_locale':True}):plot("4꞉ axes.formatter.use_locale = True after setlocale(locale.LC_ALL, '')")

Actual outcome

On Windows:

1꞉default--> should be Dez instead of Dec

2:axes.formatter.use_locale = True --> should be 0,00 instead of 0.00

3: aftersetlocale(locale.LC_ALL, '') --> this works correctly

4:axes.formatter.use_locale = True aftersetlocale(locale.LC_ALL, '') --> this works correctly too

Expected outcome

On Linux

All four cases are correct. The expected outcome on Windows is the same as on Linux.

Additional information

The issue is only on Windows, everything is fine on Linux (can't test it on MacOS but I suppose it'd be the same as on Linux).

Operating system

Windows

Matplotlib Version

3.6.3

Matplotlib Backend

No response

Python version

3.10

Jupyter version

No response

Installation

conda