What does auspicious day and auspicious rain mean?

It means that on an auspicious day and moment, things can develop and grow well, just as rain moistens and grows everything.

Auspicious days and auspicious rains mean that on an auspicious day and moment, just as rain nourishes the growth of all things, things can develop and grow well. This idiom expresses a blessing and good wishes. I hope that at a specific time and place, everything goes well and people get good luck and success. It also implies a kind of attention to the right time, the right place and the right people, and thinks that choosing a suitable time and place can bring better results.