Special Day Boosts

Originally hidden within Pokémon Diamond & Pearl, there were special days where the encounter rate or Hatch Speed would get increased/decreased. This makes a return in Pokémon Brilliant Diamond & Shining Pearl. However these games have it set so there's only positive benefits on each day

Secret Base

List of Days and Boosts

DayBoosts
January 1 Encounter Rate: +10
January 6 Encounter Rate: +10
January 11 Encounter Rate: +10
January 12 Encounter Rate: +10
Hatch Speed Reduced
January 29 Encounter Rate: +10
February 3 Encounter Rate: +10
February 11 Encounter Rate: +10
February 12 Encounter Rate: +10
February 14 Encounter Rate: +10
Hatch Speed Reduced
February 27 Encounter Rate: +10
March 3 Encounter Rate: +10
Hatch Speed Reduced
March 17 Encounter Rate: +10
March 18 Encounter Rate: +10
March 21 Encounter Rate: +10
March 25 Encounter Rate: +10
April 1 Encounter Rate: +10
Hatch Speed Reduced
April 25 Encounter Rate: +10
April 26 Encounter Rate: +10
April 29 Encounter Rate: +10
May 1 Encounter Rate: +10
Hatch Speed Reduced
May 3 Encounter Rate: +10
May 4 Encounter Rate: +10
May 5 Encounter Rate: +10
May 8 Encounter Rate: +10
May 29 Encounter Rate: +10
June 2 Encounter Rate: +10
June 11 Encounter Rate: +10
Hatch Speed Reduced
June 21 Encounter Rate: +10
July 4 Encounter Rate: +10
July 7 Encounter Rate: +10
Hatch Speed Reduced
July 14 Encounter Rate: +10
July 18 Encounter Rate: +10
July 24 Encounter Rate: +10
August 6 Encounter Rate: +10
August 9 Encounter Rate: +10
August 13 Encounter Rate: +10
August 14 Encounter Rate: +10
August 15 Encounter Rate: +10
August 16 Encounter Rate: +10
August 21 Encounter Rate: +10
Hatch Speed Reduced
August 28 Encounter Rate: +10
September 7 Encounter Rate: +10
September 11 Encounter Rate: +10
September 12 Encounter Rate: +10
September 15 Encounter Rate: +10
September 20 Encounter Rate: +10
September 23 Encounter Rate: +10
September 28 Encounter Rate: +10
October 3 Encounter Rate: +10
October 5 Encounter Rate: +10
October 12 Encounter Rate: +10
October 15 Encounter Rate: +10
October 30 Encounter Rate: +10
October 31 Encounter Rate: +10
Hatch Speed Reduced
November 1 Encounter Rate: +10
November 3 Encounter Rate: +10
November 11 Encounter Rate: +10
November 12 Encounter Rate: +10
November 16 Encounter Rate: +10
November 21 Encounter Rate: +10
Hatch Speed Reduced
November 23 Encounter Rate: +10
December 6 Encounter Rate: +10
December 8 Encounter Rate: +10
December 14 Encounter Rate: +10
December 23 Encounter Rate: +10
December 24 Encounter Rate: +10
Hatch Speed Reduced
December 25 Encounter Rate: +10
Hatch Speed Reduced
December 26 Encounter Rate: +10
December 31 Encounter Rate: +10