Because Pokémon Legends: Arceus has a dynamic overworld, Pokémon encounters and events can only occur when a certain condition is met. This can mean anything from needing to finish another mission to progress an element in an area or simply needing to be present at a certain time of day. 

There are also various different weather conditions that can cause different Pokémon to spawn or are key components in getting certain species to evolve while training them. Although this means you are reliant on the weather when trying to complete your Pokédex to a certain extent. 

Unlike the time of day, you can’t simply go through a menu and choose what weather condition will take hold of an area in Hisui. However, you can manipulate the weather by using the rest feature at a Base Camp. 

Once you have entered the area you need a specific weather condition for, head to a tent at one of the Base Camps. Then, pick whatever time of day you prefer or need to be active in for your chosen task. 

Each time you wake up, you can check your map to see what the weather condition in the area is, based on the symbol in the top right next to the area’s name. And, if it isn’t the weather you are looking for, just repeat this process until you get the one you want. 

You won’t be able to get all weather types to appear in certain areas, such as a blizzard whipping up in non-snowy areas. This is also the same method you will want to use when trying to hunt for a Full Moon, but being able to manipulate the weather is a nice bonus.