Barry Manilow and some privacy. I wouldn't try and do anything yourself as you may hurt them..
On a serious note, as long as you have a couple that like each other and the enclosure conditions are right, it will happen when they are ready.
Rain has nothing to do with it. Dont waste youre time & money. You need to condition & cycle them through the seasons properly. After that is done, itssimply "just add water!" We breed at least 6 spawnings a year, its really very simple.