Source: Tafsir al-Ahlam al-Kabir (Ibn Sirin)
Lightning in a dream indicates guidance after misguidance and the uncovering of hidden matters. It may also indicate a threat from the ruler and fear. Lightning with no rain indicates false promises.
Source: Ta'tir al-Anam fi Ta'bir al-Manam (Al-Nabulsi)
Lightning indicates laughter, glad tidings, and joy. If it burns clothes, it indicates the death of the sick or a scandal. Whoever sees lightning flashing from his house will receive goodness and sustenance.
Source: Al-Isharat fi Ilm al-Ibarat (Ibn Shahin)
Lightning is interpreted as an order from the ruler involving fear and hope. If it is with rain, it is goodness and benefit. If it is without rain, it is fear for nothing.