Pink sky at night...

Sailor's delight, Pink sky in morning sailors take warning.

This is where it originated...

Matthew 16:1-3 - NIV
¹The Pharisees and Sadducees came to Jesus and tested him by asking him to show them a sign from heaven. ² He replied, "When evening comes, you say, 'It will be fair weather, for the sky is red,' ³ and in the morning, 'Today it will be stormy, for the sky is red and overcast.'