Source: Tafsir al-Ahlam al-Kabir (Ibn Sirin)
A rainbow in a dream indicates security from fear and strife. Seeing it in red indicates bloodshed in that year; yellow indicates illness; and green indicates fertility.
Source: Ta'tir al-Anam fi Ta'bir al-Manam (Al-Nabulsi)
A rainbow indicates the appearance of strange things. Whoever sees it will get married. Seeing it on the right is good, and on the left is worry and grief.
Source: Al-Isharat fi Ilm al-Ibarat (Ibn Shahin)
A rainbow is interpreted as security, fertility, and the covenant between God and His creation. Seeing it indicates the removal of hardship and the occurrence of happy events.