For lumber to dry after it's been soaked with rain it can take from 3 to weeks before the water is completely removed from the lumber and dries out.
The lumber may dry out even faster if the weather is hot out and sunny but if it's raining again then it won't ever dry out until it stops raining.
In some cases if it's cold and damp outside it could take up to 12 weeks before the lumber fully dries out.