Mostly HP fests, but a few Teen Wolf and other fandom fests thrown in. Some of these haven't been announced yet, so they may not be running, or they may moved months. :D

Let me know if you think there's a fest that I've forgotten to include! It's very possible...

January:
TW: sterek_big_bang starts posting the 4th
HP: severus_fest starts posting the 9th

February:
HP: hprare_cliche starts posting the 1st
HP: hp_kinkfest starts posting the 1st (participating)
HP: do_me_veela starts posting the 29th

March:
HP: hp_goldenage starts posting the 1st
HP: hd_remix starts posting the 4th
HP: hp_getlucky starts posting the 14th
TW: teenwolfremix2015

April:
HP: dracotops_harry starts posting the 1st (participating)
HP: daily_deviant's Banging Birthday starts posting the 1st (participating)

May:
HP: serpentinelion's Glomp Fest starts posting the 1st
HP: wand_in_a_knot starts posting the 16th (participating)
HP: harrydracompreg starts posting the 8th
LotR: hobbitstory Big Bang starts posting the 13th

June:
HP: hprarefest starts posting the 1st
HP: hd_smoochfest n/a
TW: teenwolfbigbang starts posting the 25th
HP: hd_cliche n/a

July:
All: wipbigbang starts posting the 10th (participating)
HP: hd_tropes starts posting the 25th
HP: hd_collab n/a

August:
HP: hp_crossgenfest starts posting the 1st (participating)
HP: aftercamlann starts posting the 15th (participating)

September:
ALL: bbtp_challenge on the 1st (participating)
HP: hp_drizzle starts posting the 1st
HP: hd_familyfest starts posting the 10th
HP: hd_fan_fair starts posting the 30th
HP: hd_eighthyear n/a
HP: bottom_draco n/a
HP: hp_silencio n/a

October:
Inception: i_reversebang TBA
HP: hp_creatures start posting the 15th
HP: hp_nextgen_fest starts posting the 31st (participating)

November:
HP: hd_fanart starts posting the 1st
HP: interhouse_fest starts posting the 1st
Avengers: c_im_bigbang starts posting the 5th
TW: tw_fallharvest n/a

December:
HP: hd_erised starts posting the 1st
Merlin: winterknights starts posting the 1st
Merlin: merlin_holidays starts posting the 1st
HP: mini_fest starts posting the 1st
ST: happy_trekmas TBA
HP: hd_owlpost starts posting the 1st
ST: startrekbigbang TBA
ST: ksadvent starts posting the 1st
HP: daily_deviant's Kinky Kristmas TBA (participating)