Changing xticks to the name of the months

i have a multilevel index series whose outer level index is month and inner level index is day let say it is stored in series

print(series)

Please see the output->output

So to make plot i use the below code

series.plot.line(figsize=(20,10))

i am getting
please see the output->
output

but i want xticks to be [January, February,......,December] instead of those tuple values how can i do that???

Instead of use month only for display, maybe you should convert your MultiIndex (Month, Day) as DatetimeIndex for further analyze:

year = 2023 if len(series) == 365 else 2024  # leap year
dti = series.index.rename(['month', 'day']).to_frame().assign(year=year)
dti = pd.Index(pd.to_datetime(dti), name='Date')

series.index = dti

Output:

>>> series
Date
2023-01-01   -19.9
2023-01-02   -11.8
2023-01-03   -27.1
2023-01-04   -10.8
2023-01-05   -22.8
              ... 
2023-12-27   -26.9
2023-12-28   -12.9
2023-12-29   -10.2
2023-12-30   -15.1
2023-12-31   -29.4
Length: 365, dtype: float64

Now, you can use a formatter and a locator:

import matplotlib.dates as mdates

ax = series.plot.line(rot=45)
locator = mdates.AutoDateLocator()
formatter = mdates.DateFormatter('%B')
ax.xaxis.set_major_locator(locator)
ax.xaxis.set_major_formatter(formatter)
plt.tight_layout()
plt.show()

If need only months names is possible remove days from Multiindex by Series.droplevel and convert to datetimes with DatetimeIndex.month_name:

series.index = pd.to_datetime(series.index.droplevel(1), format='%m').month_name()
series.plot.line(figsize=(20,10))

Or if need more complex format, e.g. days with month names use matplotlib.dates.DateFormatter with convert MulitIndex to datetimes:

from matplotlib.dates import DateFormatter

series.index = pd.to_datetime([f'2020-{m}-{d}' for m, d in series.index])
    
ax = series.plot.line(figsize=(20,10))

date_form = DateFormatter("%d-%B")
ax.xaxis.set_major_formatter(date_form)