Explain the meaning of 'strange to tell' in the poem VOICE OF RAIN.

The meaning of " strange to tell" in the poem "The Voice of the Rain" written by Walt Whitman is that when the poet questions the soft falling shower, the rain, asking for its identity then to his surprise the rain replies to his question.
This replying by the rain is a strange thing to happen and so the poet says it as "strange to tell"