There's an emphasis on weather and weather effects in Pokémon Sword and Shield. Aside from one of the Gym Leaders being obsessed with manipulating type-buffs via the weather, the Wild Area is always brewing up a storm of some sort. Rain, snow, or dust, the storms in the Wild Area can also turn the tides of type advantages.
Not only can the storms in the Wild Area boost the attack power of certain pokémon's moves, but the weather also plays a factor in the type of pokémon to spawn. These effects can make a time-consuming task out of catching pokémon and completing the pokédex.
The solution is simple enough, though it does involve delving into the system settings on your Nintendo Switch. The in-game weather correlates to the date set on the Switch, so in order to change this, follow these steps: Press the home button on the Switch, select System Settings, then System, and then Date and Time. From there, turn off the Synchronize Clock. Once you have completed these steps, you will be able to freely change the date and time of the Switch. There's no need to close the game to do this. Upon re-entering the app, the weather will change automatically. Below are the various weather conditions and the correlating dates and times.
- Snow Storm - February 1, 2020 (Unlocked about mid-game, after defeating the Circhester Gym)
- Overcast - March 1, 2020
- Sandstorm - April 1, 2020 (Unlocked about mid-game)
- Clear Weather - May 1, 2020
- Heavy Fog - June 1 2020 (A post-game weather effect, available after becoming Champion)
- Intense Sun - July 1, 2020
- Rain - October 1, 2020
- Thunderstorm - November 1 2020
- Snow December 1 2020
There is a fairly significant downside to changing the date and time, however, so don't go switching times on a whim. Manipulating the Nintendo Switch in this way resets Sword and Shield's daily in-game event clock as well. A major repercussion of this is that Max Raid Battles will not reset for a full twenty-four hours after changing time in the system settings. Players could always make a run through the Wild Area and take on all Max Raid Battles beforehand, but it's good to be conscious of the side effects all the same.
Weather effects play a huge role in Sword and Shield and can slow down or speed up Pokédex completion tremendously. Changing the date and time in System Settings on the device may benefit eager trainers, but it's important to factor in the costs as it may delay progress in other endeavors. Timing really is everything in the Wild Area.
Source: IGN