Announced during the 2019 Pokémon Press Conference by Niantic CEO John Hanke, sleeping Snorlax can be encountered in Pokémon GO from May 28th, 2019 until June 3rd, 2019.

Snoozing with Snorlax!

Trainers, The next few months are going to be filled with some amazing adventures—even Pokémon are getting ready in their own ways. We’re hearing reports from all over the world that Trainers are finding Snorlax in deep slumber. Do you think they’re getting ready for an eventful summer?

Date + Time

• Tuesday, May 28, 2019, at 6 p.m. to Monday, June 3, 2019, at 1 p.m. PDT (GMT −7)

Features

• Trainers will have the chance to encounter Snorlax snoozing in the wild.
• Once caught, Snorlax will be awake and ready for battle as usual.
• Remember to take a photo during your encounter as Snorlax will only be asleep during your encounter!

Move

• Snorlax caught during the event will know the exclusive event move Yawn.

Speaking of sleeping, don’t miss a related announcement at the Pokémon 2019 Press Conference!

Time to get up (or wake up) and GO!

Source: https://pokemongolive.com/en/post/summersnooze2019/