Why Amaya means "night rain" in Japanese?

In baby name books the name Amaya is listed as Japanese and means night rain. I know the pronunciation for rain is ame (雨) and yoru (夜) for night. I am a beginning student in the language of Japanese and I would just like to know the reason for Amaya translating to night rain in a grammatical sense. On top of that, when I try to type the name Amaya in Japanese I can never get it to use the ociated kanji with this name. I would prefer a fluent Japanese speaker or native of Japan to answer this question.