Niantic has announced that more Legendary Raid Hours taking place in October 2019. For one hour every Wednesday evening, Raid Battles with the currently featured Legendary Pokémon will happen more frequently.

Get ready for spooky Legendary Raid Hours in October!

Trainers, We’re excited to announce that there will be more Legendary Raid Hours taking place in October! For one hour every Wednesday evening, Raid Battles with the currently featured Legendary Pokémon will happen more frequently.

Date + Time
From 6:00 p.m. to 7:00 p.m. in your local time zone on the following dates:

• October 2, 9, and 16, 2019: Altered Forme Giratina
• October 23 and 30, 2019: To Be Announced

Features

• There will be an increased number of five-star raids during the event hour.

As always, Trainers, be mindful of your surroundings and of others around you while playing Pokémon GO. Stay tuned for more updates. Happy raiding!

Source: https://pokemongolive.com/en/post/legendaryraidhoursoctober2019/