So basically i'll answer like this , if your feeding and its PH corrected water your feeding it then the rain comes and rains a whole bunch it will mess up the PH in the ground changing the PH of what you put and it will simulate the effects as being watered at an inconsistent PH which will lead to lock outs and stunts of growth . How ever if your just feeding it rain water that you have collected in a bucket or reservoir then if it rains for a few days its no big deal because its getting the same water , with the same PH . If you are using rain water to give to your plants then measure its PH first so that when you feed with the nutrients you can correct the PH and have it always be consistent . Thats the most important thing when they are young like that is consistent PH and of course not have her be over watered . So if it rains like crazy for a few days I would move her somewhere were shes not going to get over watered and drown to death , when they are young like that less is more and rain for couple days straight onto a small plant like that not exactly the most ideal. I hope this information shed's some light onto your grow and helps you determine what you think is best for your young plants ! -Happy Growing!