Select by date to change value

Question

df_subset looks like this:

          day        holiday       date    traffic_volume
0     Tuesday  New Years Day 2013-01-01              1439
1     Tuesday           None 2013-01-01              1502
2     Tuesday           None 2013-01-01               933
3     Tuesday           None 2013-01-01               576
4     Tuesday           None 2013-01-01               372
...       ...            ...        ...               ...
8568  Tuesday           None 2013-12-31              4504
8569  Tuesday           None 2013-12-31              3478
8570  Tuesday           None 2013-12-31              2711
8571  Tuesday           None 2013-12-31              2189
8572  Tuesday           None 2013-12-31              1457

[8573 rows x 8 columns]

I want to change the value in 'holiday' column to 'New Years Day' for those row which date is 2013-01-01, and run these codes BUT does not update:

from datetime import *
NYD=date(2013,1,1)
if df_subset.date is NYD:
    df_subset.replace('None','New Years Day')

Or are there better way to check date and update a cell in the dataframe?