While playing I haven't notice weather making any difference for play in Witcher 3. Yeah, it's there to make the gameplay realistic, but I think maybe there will be some difference in different weather on creatures or Geralt. Does weather have any measurable effects?
There are definitely some effects from weather.
The Superior Thunderbolt Potion and Foglet Decotion are both better in cloudy weather.
If you count time of day as 'weather' then Geralt is affected when he has the Sun and Stars skill. Noonwraiths and Nightwraiths are also affected by time of day.
I wouldn't count "time of day" as "weather", myself. But your point about cloudy weather is quite good, thanks! Feb 11, 2017 at 18:47
1@BryanPendleton I wouldn't really count it as weather either, but chose to include it for completeness– AngzurilFeb 11, 2017 at 19:14