Just found the perfect solution!

[bubble&squeak4ever]

Ok, this may sound really odd but, I have now found a way that the pigs can go out even if the grass is wet! Here it is.... Use a towel to dry the grass! Yes I know it sounds weird but it really works trust me!

 

[Gooksters]

Would it not still be damp and cold for them though?

 

[bubble&squeak4ever]

Would it not still be damp and cold for them though?

No I didnt find it to still be damp & cold. It wasn't too wet to start with to be honest and the sun had been on it so it wasn't cold.