You need a full moon to evolve Ursaring into Ursaluna in Pokémon Go.
This special evolution is unique to the hibernator Pokémon, where - as with the weather outside - this metrological event is also tied to when there's a full moon in real life.
This page explains the next full moon in Pokémon Go, and how to evolve Ursaring into Ursaluna when the time goes.
When is the next full moon in Pokémon Go?
The next full moon in Pokémon Go aligns with the next full moon in the real world, with the next date being Sunday, 1st February.
If you miss it, the next three dates after that are Tuesday, 3rd March, Wednesday, 1st April and Friday, 3rd May. You can see the full schedule for the year on the BBC Sky at Night Magazine or Royal Museums Greenwich.
If you were wondering if the moon's phase differs according to your location, then know it will be a full moon wherever you are - it's just the orientation that changes depending on your latitude on the planet.
This short, useful video by ScienceWorld on YouTube explains how this works:
How to evolve Ursaring into Ursaluna in Pokémon Go
To evolve Ursaring into Ursaluna in Pokémon Go, you need 100 Teddiursa Candy and a full moon. Once these requirements are met, you are able to press the 'evolve' button on the Pokémon's status screen.
Unfortunately, it's not quite as straightforward as that. Something to know is the evolution window isn't the entire day, with the exact timing being rather hard to pinpoint. According to Niantic when the feature was first announced, it works as follows:
"While the full moon is visible, you’ll be able to evolve your Ursaring into Ursaluna. Once the moon sets, you will only be able to evolve your Ursaring to Ursaluna when the moon is full again."
That suggests it's simply whenever it's night in-game, but according to the replies to this thread on the Pokémon Go subreddit, the window is both short and can vary massively, perhaps due to location: some people have only been able to evolve in the early hours (around 8am local time) and others in the early evening (after 6pm local time). As such, it's worth checking the game throughout the day, ideally in the early morning and in the early evening, to see if the option becomes available for you.
If you're struggling and you want to simply fill a Pokédex entry, an alternative option is receiving an Ursaluna from another player in a trade. But if you wish to evolve one yourself (perhaps it's a shadow version, and / or you have one with high stats that you don't want to change as part of a trade) then waiting until a possible event where the requirements are relaxed - which is what happened during the Pokémon's debut during the Teddiursa Community Day in 2022 - could be worthwhile.
There's no sign of this for now, however - so it's worth trying your best with the full moon dates shown above for now.
