Once I held these dice in my hands and rolled them for a few times I immediately felt the urge to come up with a way to put them to actual good use. With all the pirate gaming there must be uses for them!
Here is a table with the six different weather outcomes and some game system agnostic effects. The idea is to always roll two weather dice and apply both results. However, the sun will result in overall good weather, negating the other dice's effect. The "cloudy" symbol represents a simple "no effect".
The sun is shining and the weather is fine. Dot not apply any other weather effects from the other dice.
The weather is slightly cloudy but still fine overall. No further effects.
Wind is blowing, making it difficult to aim with ranged weapons.
It is raining. Blackpowder weapons may not function and need to be reloaded.
A thunder strikes a random target on the board.
Snow is falling, decreasing sight and limiting the models' movement.
For a properly piratical weather table I would probably change "Rain" to "Heavy Rain" and "Snow" to "Light Rain". This is where things really depend on the specific setting and system at hand.
What do you think?