As you play through Bugsnax you will discover that there are a lot of Bugsnax in the game. 100 of them, to be precise. They all appear in different places, under different conditions, and need to be caught in differen ways.
Some of them can only be caught then it is raining, so you may be wondering if there is a way to make it rain. The answer to this is no, there is nothing special you can do to make it rain in the game.
If you really need to catch a Bugsnack that can only appear when it is raining, the best thing to do is head to Snaxburg and sleep for a day. Keep doing this until you wake up and it is raining. The game doesn’t really have any reason not to skip days, so you won’t miss anything, as all missions and sidequests will hang around until you have completed them, even ones that need to happen at a certain time of day.