Niantic has announced that a Special Raid Weekend featuring Rayquaza will take place during Weather Week on Saturday, March 27th, 2021, at 10:00 a.m. to Sunday, March 28th, 2021, at 8:00 p.m. local time.

Rayquaza returns to raids for a limited time!

Trainers, A Special Raid Weekend featuring Rayquaza will be happening during the first-ever Weather Week event! Rayquaza, the Sky High Pokémon, is known to feed on water and particles in the atmosphere. Sounds like it’ll be eating well during this rainy and windy event!

Date + Time
Saturday, March 27, 2021, at 10:00 a.m. to Sunday, March 28, 2021, at 8:00 p.m. local time

Features

• Rayquaza will be appearing in five-star raids alongside Therian Forme Thundurus.
• Rayquaza encountered and caught during this time will know the attack Hurricane.

Rayquaza is known to only seldomly descend to the ground, so you won’t want to miss out on this chance to catch this Legendary Pokémon while it’s drawn in by Weather Week!

Please be aware of your surroundings and follow guidelines from local health authorities when playing Pokémon GO. Upcoming events are subject to change.

Source: https://pokemongolive.com/post/raidquaza-2021/?hl=en