I've removed the fests that didn't run in 2015, but when I do this list for 2016 I'll include as many as I know of and update accordingly as timelines are posted.
January:












February:







March:





April:





May:



June:



July:






August:






September:






October:










November:









December:












For 2015 H/D Fests only check
And of course, for all current fests

I hope you guys find this useful! And please let me know if I missed a fest. Sometimes it's difficult to keep up with everything. ^^
The 2016 list should be up in the next couple of days. :)