Binding of Isaac: Rebirth Wiki
Binding of Isaac: Rebirth Wiki

The following table is a list of curated daily runs for Daily Challenges:

Date Event, if any Peculiarities
January 1 New Year's Starts with 99 bombs (not 15►Pyro Pyro), blindfolded. Only bomb items can be found in Treasure Room Item Pool.
January 14 National Dress Up Your Pet Day Isaac, starts with 15►Guppy's Head Guppy's Head, 15►Guppy's Collar Guppy's Collar, and 15►Guppy's Tail Guppy's Tail, no item rooms.
January 16 National Nothing Day Apollyon, no item rooms, no shops.
January 27 Thomas Crapper Day ???, starts with 15►Flush! Flush!, 15►Number One Number One, 15►Butt Bombs Butt Bombs, Added in Afterbirth15►No. 2 No. 2 and 15►E Coli E Coli, no item rooms, no shops.
February 2 Groundhog Day Same character as the day before.
February 9 National Toothache Day Cain, starts with 15►Monstro's Tooth Monstro's Tooth, Added in Afterbirth †15►Dead Tooth Dead Tooth, 15►Tough Love Tough Love and 50 luck, no item rooms.
February 11 National "Don't Cry Over Spilled Milk" Day Magdalene, starts with Added in Afterbirth15►Milk! Milk! and 15►Soy Milk Soy Milk.
February 14 Valentine's Day Magdalene, starts with Added in Afterbirth15►Friendly Ball Friendly Ball, 15►The Battery The Battery, 15►Mom's Eyeshadow Mom's Eyeshadow and 7 luck.
February 18 National Battery Day Isaac, starts with 15►9 Volt 9 Volt, 15►The Battery The Battery, Added in Afterbirth15►Charged Baby Charged Baby, 15►Mom's Purse Mom's Purse, AAA Battery AAA Battery and Added in AfterbirthWatch Battery Watch Battery.
March 2 Edmund's birthday Isaac to Mega Satan, starts with undroppable The Left Hand The Left Hand.
March 4 Holy Experiment Day Magdalene, starts with Added in Afterbirth †15►Eucharist Eucharist, Added in Afterbirth15►Immaculate Conception Immaculate Conception, and Added in Afterbirth15►Seraphim Seraphim, no Item Rooms.
March 17 St. Patrick's day Cain to Mega Satan, starts with 18 luck.
March 20 National Alien Abduction Day Isaac, starts with Added in Afterbirth †15►Cone Head Cone Head, 15►The Parasite The Parasite, and Added in Afterbirth15►Tractor Beam Tractor Beam. No item rooms.
March 22 National "Goof off" day Isaac, starts with extreme range; tears follow random patterns.
Easter Easter Lazarus, starts with 15►Blood of the Martyr Blood of the Martyr, 15►Stigmata Stigmata, no item rooms.
April 1 April fools Old Man Keeper, random trinkets and items upon pickups.
April 10 National siblings day Lilith, starts with 15►Brother Bobby Brother Bobby, 15►Ghost Baby Ghost Baby, 15►Little Gish Little Gish, 15►Little Steven Little Steven, 15►Mongo Baby Mongo Baby, and 15►Sister Maggy Sister Maggy.
April 15 National That Sucks day Lazarus, starts with 15►Bob's Brain Bob's Brain, Added in Afterbirth15►Curse of the Tower Curse of the Tower, 15►Cursed Eye Cursed Eye, 15►Dead Cat Dead Cat, and Tick Tick; no item rooms.
April 22 National Jelly Bean day Maggie, starts with 15►9 Volt 9 Volt, 15►The Black Bean The Black Bean, Added in Afterbirth †15►Linger Bean Linger Bean, and Added in Afterbirth †15►Wait What? Wait What?, no item rooms.
May 4 May the 4th be with you! Isaac, starts with Added in Afterbirth15►Spear of Destiny Spear of Destiny and 15►Technology Technology.
May 8 Mothers' day Isaac, starts with 15►Mom's Lipstick Mom's Lipstick, 15►Mom's Pad Mom's Pad and 15►Mom's Eye Mom's Eye, no item rooms.
May 13 National "Stamp Out Hunger" and Frog Jump day Magdalene, starts with 15►How to Jump How to Jump and 15►Thunder Thighs Thunder Thighs. Using How to Jump will send out rock waves similar to Wait What?. No item rooms.
May 17 National "Pack Rat Day" Isaac, starts with 15►D20 D20 and Added in Afterbirth15►Sack Head Sack Head.
May 30 Memorial day The Lost, no tears, 3 familiars and Conjoined.
June 2 Magdalene, starts with 15►Blank Card Blank Card, II - The High Priestess II - The High Priestess and undroppable Mom's Toenail Mom's Toenail, no item rooms.
June 5 World Environment Day ???, starts with 15►Gnawed Leaf Gnawed Leaf and Added in Afterbirth15►Restock Restock.
June 18 Fathers' day Cain, starts with 15►A Dollar A Dollar.
June 19 Fathers' day Cain, starts with 15►Daddy Longlegs Daddy Longlegs and 15►Dad's Key Dad's Key, no item rooms.
June 25 Pride day The Lost, rainbow items.
July 2 I Forgot Day ???, starts with 15►Forget Me Now Forget Me Now. Permanent Curse of the Lost, Curse of the Blind, and Curse of the Unknown.
July 4 Independence day Samson, starts with 15►Dr. Fetus Dr. Fetus and Added in Afterbirth15►Scatter Bombs Scatter Bombs.
July 11 ???, to Sheol. Starts with Added in Afterbirth †15►Compost Compost, 15►The Mulligan The Mulligan, and 15►Rotten Baby Rotten Baby. No Treasure Rooms.
July 13 Embrace Your Geekness Day Lazarus, starts with 15►20/20 20/20, 15►Monster Manual Monster Manual, 15►Robo-Baby Robo-Baby, and a Dice Shard. No Treasure Rooms.
August 15 National Relaxation day Magdalene, starts with 15►Brimstone Brimstone, 15►Holy Mantle Holy Mantle, 15►Rubber Cement Rubber Cement, 15►Spoon Bender Spoon Bender, and 15►Tammy's Head Tammy's Head; no item rooms.
August 16 National Tell a Joke day The Keeper, every pill is Explosive Diarrhea.
August 22 National Be an Angel day Isaac, starts with 15►Fate Fate, Added in Afterbirth15►Holy Light Holy Light, and 15►Sacred Heart Sacred Heart.
September 5 National Be Late for Something day Magdalene to Mom. Starts with 15►Broken Watch Broken Watch, 15►Stop Watch Stop Watch, and 0.15 Speed
September 17 National Apple Dumpling day Cain, every boss item is Added in Afterbirth †15►Apple! Apple!.
September 22 Elephant Appreciation Day Magdalene to The Chest, starts with 15►Bucket of Lard Bucket of Lard and 15►Thunder Thighs Thunder Thighs.
October 6 National Mad Hatter day Judas, starts with 15►Dr. Fetus Dr. Fetus and Added in Afterbirth15►Scatter Bombs Scatter Bombs. Only bomb items can be found in Treasure Room Item Pool.
October 7 Isaac to The Cathedral. Starts with Added in Afterbirth15►Chaos Chaos.
October 31 Halloween Eve, starts with Added in Afterbirth15►Sack Head Sack Head.
November 1 Day of the Dead The Lost, starts with 15►Dead Cat Dead Cat, without 15►Holy Mantle Holy Mantle and 15►D4 D4.
November 11 Veterans' day The Lost, no item rooms.
November 13 World Kindness day Isaac to It Lives; starts with 15►A Quarter A Quarter, 15►Blank Card Blank Card + XX - Judgement XX - Judgement, 15►Habit Habit, and 15►PHD PHD.
November 19 National "Have a Bad Day" day ??? to Mega Satan; starts with 15►Bob's Brain Bob's Brain, 15►Cursed Eye Cursed Eye, Added in Afterbirth15►Curse of the Tower Curse of the Tower, and Added in Afterbirth15►Scatter Bombs Scatter Bombs. No item rooms.
November 20 Thanksgiving Starts with 15►Cupid's Arrow Cupid's Arrow. Every boss item is 15►Rotten Meat Rotten Meat.
December 5 Krampusnacht Isaac to Satan; starts with 15►A Lump of Coal A Lump of Coal and 15►Mitre Mitre. Devil Room spawns on first floor with Krampus.
December 6 Satoru Iwata's birthday Iwata's sprite, starts with 15►The Gamekid The Gamekid and Cartridge Cartridge. Nintendo-themed items in special rooms.
December 23 National Festivus day Only 15►The Body The Body, 15►The Soul The Soul, 15►The Mind The Mind and 15►Godhead Godhead can be found in Treasure Room Item Pool.
December 25 Christmas Isaac, starts with 15►A Quarter A Quarter, 15►A Lump of Coal A Lump of Coal, and wearing a Christmas hat. Every item room has 2 items.
December 31 New Year's Eve Isaac, starts with Added in Afterbirth15►More Options More Options and 15►There's Options There's Options.

The full list of the remaining undisclosed dailies isn't published to avoid spoiling content.