Confirming The Shiny Bonus on Articuno Day

On Saturday July 7th the highly anticipated Articuno Day arrived – promising a chance at a shiny variant of the legendary bird. Continuing the The Silph Research Group’s recent efforts to deduce the base shiny rate and all boosted rates, our researchers set out with a mission to record as many Articuno Raids as possible and amass a valuable dataset.


When the dust settled, over 3,000 Raids were recorded in the three-hour period. Based on this data we have approximated the shiny rate for the legendary bird during the event to be approximately:

1 in 20

with 95% confidence interval of 1 in 17.7 to 1 in 24.2.

Articuno’s shiny rate is statistically indistinguishable from the 1 in 18 previously reported for the potentially shiny Legendary Raid Bosses Lugia, Ho-Oh, and Kyogre. It is therefore likely that the shiny rate for Articuno remained constant, despite the shorter event duration and change in Raid level.

As a reward for completing Professor Willow’s Global Challenge during GO Fest, travelers around the world have also unlocked Zapdos Day for Saturday, July 21, with the same format as Articuno Day. We are very much looking forward to this event, and the Silph Research Group will continue to monitor the probability of encountering a shiny Zapdos. We expect that the shiny rate will remain constant at around 1 in 20 for Zapdos, and will likely hold for Moltres Day as well, which we anticipate to follow.

Practical Application

Zapdos Day, like Articuno Day, will grant five free Raid Passes. The probability of encountering a shiny with 5 Raid Passes is 1 – 0.95^5 or about 22.6% during the event. These Legendary Day Pokémon are arguably among the rarest shiny Pokémon out there! Happy shiny hunting, travelers!

– Scientist Ansku –

P.S. Thanks once again to Scientist Titleist12 for the calculations.