Most often in August, 31 days.
Highest follower count seen that year: 88,507.
July
Jul 26 00:00–01:00, 22:00–24:00 Jul 27 00:00–07:00, 16:00–20:00, 22:00–23:00 Jul 28 05:00–07:00, 17:00–19:00 Jul 29 01:00–05:00, 16:00–19:00 Jul 30 01:00–06:00, 16:00–19:00 Jul 31 02:00–06:00
August
Aug 1 02:00–07:00, 17:00–19:00 Aug 2 00:00–03:00, 06:00–07:00, 14:00–18:00, 22:00–24:00 Aug 3 00:00–06:00, 16:00–21:00 Aug 4 04:00–08:00, 18:00–20:00 Aug 5 18:00–19:00 Aug 6 01:00–08:00, 17:00–19:00 Aug 7 03:00–06:00, 17:00–21:00 Aug 8 02:00–07:00 Aug 9 02:00–06:00, 23:00–24:00 Aug 10 00:00–04:00, 15:00–18:00, 20:00–22:00 Aug 11 06:00–07:00, 17:00–19:00 Aug 12 01:00–07:00, 17:00–21:00 Aug 13 05:00–06:00 Aug 14 03:00–08:00 Aug 15 02:00–08:00 Aug 16 04:00–07:00 Aug 17 03:00–07:00, 22:00–24:00 Aug 18 00:00–03:00 Aug 19 02:00–05:00 Aug 20 01:00–02:00, 05:00–06:00, 13:00–19:00 Aug 21 05:00–07:00, 17:00–19:00 Aug 22 05:00–09:00, 22:00–24:00 Aug 23 00:00–03:00, 05:00–07:00, 21:00–24:00 Aug 24 00:00–03:00, 05:00–06:00 Aug 25 04:00–06:00, 17:00–19:00, 22:00–24:00 Aug 26 00:00–05:00, 17:00–19:00 Aug 27 00:00–03:00, 05:00–07:00, 15:00–20:00 Aug 28 00:00–02:00, 04:00–06:00, 17:00–19:00 Aug 29 00:00–03:00, 05:00–07:00, 17:00–19:00 Aug 30 02:00–06:00, 23:00–24:00 Aug 31 00:00–07:00, 15:00–19:00
September
Sep 1 02:00–07:00, 16:00–19:00 Sep 2 01:00–06:00, 16:00–19:00, 22:00–24:00 Sep 3 00:00–07:00, 18:00–19:00 Sep 4 03:00–07:00, 16:00–19:00 Sep 5 01:00–07:00, 16:00–17:00 Sep 6 01:00–06:00 Sep 7 04:00–09:00, 18:00–24:00 Sep 8 00:00–01:00, 18:00–19:00, 23:00–24:00 Sep 9 00:00–07:00, 16:00–19:00 Sep 10 01:00–06:00, 15:00–19:00 Sep 11 00:00–07:00, 15:00–20:00 Sep 12 01:00–07:00, 14:00–19:00 Sep 13 01:00–07:00 Sep 14 00:00–06:00, 17:00–19:00 Sep 15 03:00–07:00, 16:00–20:00 Sep 16 06:00–07:00, 15:00–16:00 Sep 17 03:00–06:00, 17:00–18:00 Sep 18 02:00–06:00 Sep 19 05:00–07:00, 15:00–19:00 Sep 20 02:00–06:00, 16:00–20:00, 22:00–24:00 Sep 21 00:00–01:00, 23:00–24:00 Sep 22 00:00–04:00, 17:00–19:00, 23:00–24:00 Sep 23 00:00–03:00, 05:00–07:00 Sep 24 00:00–07:00, 17:00–19:00 Sep 25 02:00–06:00, 16:00–19:00 Sep 26 01:00–06:00, 15:00–20:00 Sep 27 05:00–07:00, 16:00–19:00 Sep 28 00:00–03:00, 05:00–07:00, 16:00–19:00 Sep 29 05:00–07:00, 17:00–19:00 Sep 30 01:00–07:00, 17:00–20:00
October
Oct 1 01:00–02:00, 06:00–07:00, 16:00–19:00 Oct 2 01:00–07:00, 17:00–19:00 Oct 3 02:00–04:00 Oct 4 01:00–07:00, 16:00–18:00 Oct 5 04:00–07:00, 15:00–19:00 Oct 6 01:00–05:00 Oct 17 02:00–06:00, 16:00–19:00 Oct 18 02:00–06:00, 16:00–17:00 Oct 20 01:00–06:00, 17:00–19:00 Oct 21 17:00–19:00 Oct 22 02:00–07:00, 16:00–19:00 Oct 23 04:00–06:00, 17:00–20:00 Oct 24 03:00–07:00, 17:00–19:00 Oct 25 00:00–01:00 Oct 26 16:00–20:00 Oct 27 18:00–20:00 Oct 28 16:00–19:00 Oct 29 01:00–05:00, 17:00–19:00 Oct 30 02:00–06:00, 16:00–19:00 Oct 31 16:00–20:00
November
Nov 1 03:00–06:00 Nov 2 05:00–09:00, 17:00–20:00 Nov 3 00:00–07:00, 17:00–21:00, 23:00–24:00 Nov 4 00:00–05:00, 17:00–19:00 Nov 5 03:00–06:00, 17:00–19:00 Nov 6 04:00–06:00, 17:00–19:00 Nov 7 03:00–06:00, 18:00–19:00 Nov 8 02:00–03:00 Nov 9 01:00–04:00, 17:00–24:00 Nov 10 00:00–02:00, 04:00–05:00, 17:00–20:00 Nov 11 04:00–06:00, 16:00–19:00 Nov 12 01:00–06:00, 18:00–20:00 Nov 13 01:00–06:00, 16:00–19:00 Nov 14 16:00–19:00 Nov 15 02:00–06:00, 16:00–17:00 Nov 16 00:00–06:00, 18:00–24:00 Nov 17 00:00–01:00 Nov 18 00:00–07:00 Nov 20 01:00–04:00, 18:00–19:00 Nov 21 15:00–19:00 Nov 22 14:00–17:00, 22:00–24:00 Nov 23 00:00–04:00, 20:00–23:00 Nov 25 02:00–04:00, 17:00–19:00 Nov 26 17:00–20:00 Nov 27 01:00–06:00, 17:00–19:00 Nov 28 17:00–19:00 Nov 29 02:00–06:00 Nov 30 04:00–06:00, 19:00–24:00
December
Dec 1 00:00–01:00, 18:00–21:00 Dec 2 18:00–19:00 Dec 3 05:00–06:00, 17:00–19:00 Dec 4 18:00–19:00 Dec 5 03:00–05:00, 18:00–20:00 Dec 7 21:00–24:00 Dec 8 00:00–05:00, 21:00–24:00 Dec 9 00:00–02:00 Dec 10 18:00–20:00 Dec 11 17:00–19:00 Dec 12 02:00–06:00 Dec 13 05:00–06:00, 16:00–18:00, 22:00–24:00 Dec 14 00:00–05:00, 20:00–24:00 Dec 15 06:00–07:00, 18:00–19:00 Dec 16 03:00–06:00, 18:00–19:00 Dec 17 17:00–19:00 Dec 19 18:00–20:00 Dec 20 03:00–07:00 Dec 21 00:00–05:00, 19:00–24:00 Dec 22 16:00–19:00 Dec 23 03:00–08:00 Dec 24 04:00–08:00 Dec 25 01:00–08:00, 19:00–24:00 Dec 26 00:00–07:00, 16:00–17:00 Dec 27 02:00–06:00, 20:00–23:00 Dec 28 17:00–24:00 Dec 30 03:00–06:00 Dec 31 00:00–07:00, 22:00–24:00