Python Pandas : pandas.to_datetime() is switching day & month when day is less than 13

You can use the dayfirst parameter in pd.to_datetime.

pd.to_datetime(df.tmp, dayfirst=True)

Output:

0   2015-06-11 00:56:55
1   2015-06-11 04:16:38
2   2015-06-12 16:13:30
3   2015-06-12 21:24:03
4   2015-06-13 02:31:44
5   2015-06-13 02:37:49
Name: tmp, dtype: datetime64[ns]