I.e., hope of rain - an oft-recurring Quranic symbol of faith and spiritual life (cf: 13:12).
Translation
(
30:24) And among His wonders is this: He displays before you the lightning, giving rise to [both] fear and hope,
[16] and sends down water from the skies, giving life thereby to the earth after it had been lifeless: in this, behold, there are messages indeed for people who use their reason!