import pandas as pd
from pandas import Series

import matplotlib.pyplot as plt

temperature = pd.read_csv(
    "https://milliams.com/courses/data_analysis_python/cetml1659on.txt",  # file name
    skiprows=6,  # skip header
    delim_whitespace=True,  # whitespace separated
    na_values=['-99.9', '-99.99'],  # NaNs
)

year_plot = temperature['JAN'].plot()
year_plot = temperature['JUN'].plot()

year_plot.set_xlabel(r'Year')
year_plot.set_ylabel(r'Temperature ($^\circ$C)')

plt.show()

Introduction to Data Analysis in Python