Fontsize in xticks not responding correctly

Question

I am trying to change the fontsize of xticks and yticks in python. The plot represents daily averages for a random location for December 2019.

My problem is that I sent set yticks fontsize to 26 but only the label od Dec2019 changes but not the numbers in xticks.

Here is the essential part of the code: Here is the part of the code final = reduce(lambda left,right: pd.merge(left,right, left_index=True, right_index=True), dfs_filtered)

final.resample('D').mean().plot( figsize=(12,9),marker='.'); plt.legend(etik,fontsize=13)
plt.ylabel('Daily mean concentration $(μg/m^3)$',fontsize=13); plt.xlabel('Day',fontsize=13)
plt.xlim(pd.Timestamp('2019-12-01'),pd.Timestamp('2019-12-31'))

plt.xticks(fontsize=26); plt.yticks(fontsize=26)

plt.ylim(bottom=0); plt.margins(x=0)
plt.title(list(aerosols.keys())[n]+' ('+ABBR[list(aerosols.keys())[n]]+')',fontsize=13)

plt.show()

Explanation: The problem was the existence of label Dec2019. This label was considered by python as major, downgrading the 02,09,16,23,30 to minor. In y axis, there was not a problem as 2,4,6,8,10 were considered as major. Also, the proposed question does not answer to my question, although I used parts of code from the proposed one.

Answer 1

using the answer @Bill Huang proposed, it seems that the xticks were considered by Python as minor, while the label Dec 2019 and yticks as major.

fig, ax = plt.subplots()
ax.tick_params(axis='both', which='major', labelsize=26)
ax.tick_params(axis='both', which='minor', labelsize=26)

final.resample('D').mean().plot( figsize=(12,9),ax=ax,marker='.'); plt.legend(etik,fontsize=13)
plt.ylabel('Daily mean concentration $(μg/m^3)$',fontsize=13); plt.xlabel('Day',fontsize=13)
plt.xlim(pd.Timestamp('2019-12-01'),pd.Timestamp('2019-12-31'))

plt.ylim(bottom=0); plt.margins(x=0)
plt.title(list(aerosols.keys())[n]+' ('+ABBR[list(aerosols.keys())[n]]+')',fontsize=13)

plt.show()