strftime
См. http://strftime.org/
s = pd.date_range('2012-01-01', '2012-12-31', freq='400H').to_series()
s.dt.strftime('%B %d, %I %p')
2012-01-01 00:00:00 January 01, 12 AM
2012-01-17 16:00:00 January 17, 04 PM
2012-02-03 08:00:00 February 03, 08 AM
2012-02-20 00:00:00 February 20, 12 AM
2012-03-07 16:00:00 March 07, 04 PM
2012-03-24 08:00:00 March 24, 08 AM
2012-04-10 00:00:00 April 10, 12 AM
2012-04-26 16:00:00 April 26, 04 PM
2012-05-13 08:00:00 May 13, 08 AM
2012-05-30 00:00:00 May 30, 12 AM
2012-06-15 16:00:00 June 15, 04 PM
2012-07-02 08:00:00 July 02, 08 AM
2012-07-19 00:00:00 July 19, 12 AM
2012-08-04 16:00:00 August 04, 04 PM
2012-08-21 08:00:00 August 21, 08 AM
2012-09-07 00:00:00 September 07, 12 AM
2012-09-23 16:00:00 September 23, 04 PM
2012-10-10 08:00:00 October 10, 08 AM
2012-10-27 00:00:00 October 27, 12 AM
2012-11-12 16:00:00 November 12, 04 PM
2012-11-29 08:00:00 November 29, 08 AM
2012-12-16 00:00:00 December 16, 12 AM
Freq: 400H, dtype: object