Skylark by Patricia MacLachlan (sequel to Sarah, Plain and Tall)
There is a drought out on the prairie where Papa, Sarah, Anna,and Caleb lived. No one was happy, everybody was sad. One day Sarah, Anna, and Caleb went to Maine(Sarah's homeland). When they were in Maine it rained! On their last day in Maine Papa came! Papa and Sarah had a very special surprise for Anna and Caleb. If you want to find out what the surprise was read this book for yourself.