morning rainbow
A rainbow seen in the morning. In Japanese folk belief, a morning rainbow is considered a sign of coming rain.
There's a morning rainbow, so it might rain today.
My grandmother told me to take an umbrella when she saw a morning rainbow.
Compound of 朝 (あさ, 'morning') and 虹 (にじ, 'rainbow'). The reading にじ for 虹 is standard.