Mature pine cones will open or close depending on the weather, sun or rain.
Cones that are on the ground and are open will closeup when it rains, then reopen with sunshine. They will continue to open and close in sun and rain. This is true for freshly fallen cones and for ones that have been on the ground a long time.
When conditions are favorable and dry, cones will open to release their seeds. Cones close when conditions are unfavorable and rainy. The closing and opening of a cone’s scales is caused by swelling and shrinking of the cone’s plant cells. Closing occurs as the cells expand when wet and the scales shut tight, then the cells shrink as they dry out and the scales open.
If you would like to see pine cones close and open, try this experiment. Take some open cones, place them in a pan of water and watch them close, then take them out, let them dry and see them open again.