I get fresh eggs from a local egg ranch. Today they only had double yolk jumbo eggs. My cakes are not rising as usual and they are very dense. They almost look under cooked but they are not. Could the double yolk be the cause? Also it's pretty humid today, will that affect baking too?

I just took another cake out of the oven. It feels heavy and didn't rise as usual too. I cut a cooled cake and it was almost rubbery!

AIt is bound to make a difference; double-yolk eggs are much larger than regular eggs. You might want to try measuring the eggs to get the right amount. A standard large egg is around 2 oz. I think double-yolk eggs are closer to 3 oz. This should help but the yolk to white ratio will still be different so you results might not be exactly what you get with regular eggs. The other thing that might have made you cakes turn out the way they did is if you were concerned about how they were baking and opened the oven frequently to check. Maybe that sounds dorky, but it is something I learned the hard way! I now know not to open the oven during the first half of baking time. The resulting temperature variations cause weirdness in baking.

Definitely!

Yolks contain a lot of fat, so if you have double the amount of yolks in your batter, the ratio of fat to sugar is off and the cake will rise a lot less as it is "heavier" and the sugar will have less ability to act as a raising agent.
 

Measure your egg yolks by weight instead of count. A large egg yolk weights .75 ounces. So if your recipe calls for 4 yolks add 3 ounces of yolks and everything will remain in balance.

Thank you all so much! I love fresh jumbo eggs and I will definitely start to weigh them.

AYep! I add a few extra yolks (saved from my white cakes) to my chocolate cake to make it a bit more dense. And to my Almond cake, as well. It gives it a texture almost like a pound cake, but I keep the weights the same. I ALWAYS weigh my eggs.