Most often in August, 31 days.
Highest follower count seen that year: 1,386.
July
Jul 28 00:00–01:00, 16:00–17:00, 20:00–24:00 UTC Jul 29 00:00–03:00, 09:00–11:00, 14:00–16:00, 18:00–24:00 UTC Jul 30 01:00–02:00, 22:00–24:00 UTC Jul 31 00:00–01:00, 22:00–24:00 UTC
August
Aug 1 00:00–04:00, 14:00–18:00, 21:00–24:00 UTC Aug 2 08:00–12:00, 19:00–20:00 UTC Aug 3 00:00–02:00, 18:00–20:00 UTC Aug 4 16:00–17:00, 19:00–24:00 UTC Aug 5 07:00–08:00, 13:00–18:00, 20:00–22:00 UTC Aug 6 06:00–10:00, 13:00–15:00 UTC Aug 7 05:00–08:00, 11:00–12:00, 18:00–23:00 UTC Aug 8 06:00–07:00, 10:00–13:00, 15:00–18:00, 20:00–22:00 UTC Aug 9 07:00–09:00, 11:00–13:00, 18:00–24:00 UTC Aug 10 00:00–01:00, 07:00–10:00, 14:00–15:00, 22:00–24:00 UTC Aug 11 00:00–01:00, 08:00–10:00, 15:00–16:00, 23:00–24:00 UTC Aug 12 10:00–13:00, 18:00–23:00 UTC Aug 13 06:00–10:00, 15:00–18:00, 20:00–23:00 UTC Aug 14 07:00–10:00, 12:00–13:00, 18:00–20:00 UTC Aug 15 07:00–09:00, 21:00–24:00 UTC Aug 16 00:00–01:00, 09:00–12:00, 15:00–24:00 UTC Aug 17 00:00–02:00, 06:00–09:00, 12:00–13:00, 18:00–23:00 UTC Aug 18 08:00–10:00, 12:00–15:00, 18:00–24:00 UTC Aug 19 00:00–03:00, 12:00–14:00, 17:00–23:00 UTC Aug 20 08:00–13:00, 16:00–23:00 UTC Aug 21 11:00–23:00 UTC Aug 22 00:00–01:00, 13:00–14:00, 19:00–23:00 UTC Aug 23 08:00–13:00, 20:00–24:00 UTC Aug 24 00:00–02:00, 08:00–10:00, 19:00–21:00 UTC Aug 25 16:00–24:00 UTC Aug 26 00:00–02:00, 07:00–08:00, 18:00–23:00 UTC Aug 27 10:00–23:00 UTC Aug 28 09:00–10:00, 12:00–14:00, 16:00–17:00, 20:00–23:00 UTC Aug 29 13:00–18:00, 20:00–23:00 UTC Aug 30 00:00–01:00, 10:00–15:00, 18:00–24:00 UTC Aug 31 08:00–11:00, 16:00–20:00, 23:00–24:00 UTC
September
Sep 1 00:00–02:00, 11:00–17:00, 19:00–24:00 UTC Sep 2 09:00–12:00, 20:00–24:00 UTC Sep 3 11:00–14:00, 18:00–24:00 UTC Sep 4 08:00–09:00, 12:00–14:00, 19:00–24:00 UTC Sep 5 00:00–04:00, 19:00–24:00 UTC Sep 6 00:00–02:00, 16:00–24:00 UTC Sep 7 00:00–02:00, 20:00–24:00 UTC Sep 8 00:00–06:00, 17:00–18:00, 21:00–22:00 UTC Sep 9 17:00–24:00 UTC Sep 10 00:00–01:00, 14:00–15:00, 19:00–24:00 UTC Sep 11 00:00–05:00 UTC Sep 15 05:00–08:00, 19:00–22:00 UTC Sep 16 06:00–12:00, 18:00–19:00, 21:00–23:00 UTC Sep 17 09:00–11:00, 19:00–23:00 UTC Sep 18 01:00–03:00, 13:00–15:00, 20:00–24:00 UTC Sep 19 00:00–04:00, 19:00–24:00 UTC Sep 20 00:00–05:00, 16:00–17:00, 19:00–24:00 UTC Sep 21 00:00–04:00, 16:00–24:00 UTC Sep 22 00:00–04:00, 11:00–13:00, 21:00–24:00 UTC Sep 23 00:00–03:00 UTC Sep 24 09:00–11:00, 16:00–17:00, 20:00–24:00 UTC Sep 25 00:00–04:00, 21:00–23:00 UTC Sep 26 10:00–11:00, 18:00–24:00 UTC
October
Oct 7 18:00–24:00 UTC Oct 8 00:00–03:00, 08:00–10:00, 14:00–23:00 UTC Oct 9 14:00–15:00, 17:00–22:00 UTC Oct 10 13:00–16:00, 18:00–24:00 UTC Oct 11 00:00–01:00, 09:00–11:00, 17:00–24:00 UTC Oct 12 16:00–22:00 UTC Oct 13 13:00–14:00, 16:00–24:00 UTC Oct 14 00:00–01:00, 06:00–07:00, 10:00–24:00 UTC Oct 15 00:00–01:00, 08:00–11:00, 13:00–24:00 UTC Oct 16 07:00–09:00, 13:00–14:00, 16:00–17:00, 19:00–22:00 UTC Oct 17 08:00–12:00, 14:00–24:00 UTC Oct 18 03:00–04:00, 08:00–11:00, 13:00–14:00, 18:00–22:00 UTC Oct 19 18:00–20:00, 22:00–24:00 UTC Oct 20 09:00–11:00, 14:00–15:00, 17:00–19:00, 22:00–24:00 UTC Oct 21 14:00–16:00, 18:00–24:00 UTC Oct 22 00:00–01:00, 08:00–09:00, 11:00–12:00, 14:00–15:00, 19:00–24:00 UTC Oct 23 00:00–01:00, 07:00–11:00, 16:00–21:00 UTC Oct 24 07:00–10:00, 15:00–17:00, 20:00–23:00 UTC Oct 25 09:00–10:00, 15:00–16:00, 18:00–23:00 UTC Oct 26 14:00–15:00 UTC Oct 27 16:00–24:00 UTC Oct 28 00:00–01:00, 08:00–09:00, 12:00–14:00, 16:00–24:00 UTC Oct 29 00:00–02:00, 08:00–12:00, 14:00–16:00, 18:00–24:00 UTC Oct 30 00:00–02:00, 09:00–12:00, 17:00–24:00 UTC Oct 31 10:00–15:00, 18:00–20:00, 22:00–24:00 UTC
November
Nov 1 00:00–03:00, 13:00–17:00, 19:00–24:00 UTC Nov 2 00:00–02:00, 08:00–09:00, 13:00–16:00, 20:00–22:00 UTC Nov 3 11:00–14:00, 17:00–24:00 UTC Nov 4 00:00–03:00, 08:00–11:00, 15:00–24:00 UTC Nov 5 00:00–02:00, 06:00–07:00 UTC Nov 11 18:00–23:00 UTC Nov 12 07:00–22:00 UTC Nov 13 08:00–24:00 UTC Nov 14 00:00–02:00, 09:00–11:00, 17:00–24:00 UTC Nov 15 00:00–02:00, 09:00–24:00 UTC Nov 16 00:00–02:00, 07:00–10:00, 12:00–14:00, 19:00–24:00 UTC Nov 17 00:00–04:00, 08:00–13:00, 18:00–24:00 UTC Nov 18 00:00–02:00, 06:00–14:00, 17:00–18:00, 20:00–24:00 UTC Nov 19 01:00–02:00, 06:00–08:00, 11:00–15:00, 17:00–24:00 UTC Nov 20 00:00–03:00, 09:00–14:00, 16:00–24:00 UTC Nov 21 00:00–03:00, 08:00–14:00, 17:00–24:00 UTC Nov 22 00:00–04:00, 07:00–14:00, 16:00–18:00, 22:00–23:00 UTC Nov 23 01:00–03:00, 12:00–13:00, 18:00–24:00 UTC Nov 24 00:00–04:00, 06:00–08:00, 18:00–19:00, 21:00–24:00 UTC Nov 25 00:00–02:00, 09:00–15:00, 19:00–24:00 UTC Nov 26 00:00–02:00, 08:00–10:00, 13:00–14:00, 18:00–24:00 UTC Nov 27 00:00–02:00, 10:00–14:00, 17:00–24:00 UTC Nov 28 00:00–02:00, 05:00–06:00 UTC
December
Dec 1 15:00–23:00 UTC Dec 2 06:00–08:00, 14:00–15:00, 17:00–24:00 UTC Dec 3 03:00–06:00, 08:00–10:00, 13:00–15:00, 17:00–18:00, 21:00–24:00 UTC Dec 4 02:00–03:00, 06:00–12:00, 14:00–15:00, 17:00–24:00 UTC Dec 5 00:00–02:00, 07:00–24:00 UTC Dec 6 04:00–06:00, 17:00–22:00 UTC Dec 7 09:00–11:00, 20:00–24:00 UTC Dec 8 00:00–03:00, 06:00–13:00, 18:00–24:00 UTC Dec 9 01:00–04:00, 08:00–10:00, 12:00–16:00, 20:00–24:00 UTC Dec 10 00:00–01:00, 04:00–07:00, 09:00–16:00, 19:00–24:00 UTC Dec 11 00:00–01:00, 10:00–16:00, 20:00–23:00 UTC Dec 12 21:00–23:00 UTC Dec 13 00:00–05:00, 09:00–10:00 UTC Dec 14 00:00–03:00 UTC Dec 15 21:00–24:00 UTC Dec 16 00:00–02:00 UTC Dec 17 05:00–10:00, 12:00–14:00, 17:00–18:00 UTC Dec 18 08:00–10:00, 12:00–16:00 UTC Dec 19 20:00–24:00 UTC Dec 20 00:00–02:00, 06:00–07:00, 23:00–24:00 UTC