The time for the prayer for rain (salat al-istisqa’)
Question

I want to ask about the prayer for rain (salat al-istisqa’): is it permissible to offer this prayer other than at the time of sunrise, like the Eid prayer, such as – for example – praying after Zuhr or Maghrib or `Isha’?
Praise be to Allah.If praying for rain is done by offering supplication (du`a’) only, it is permissible at any time. If it is accompanied by the formal prayer (salah), it is permissible to offer it at any time, except at the times when praying is disliked (makruh), according to the majority of jurists.
Ibn Qudamah (may Allah have mercy on him) said in al-Mughni, 3/337: There is no specific time for the prayer for rain, except that it should not be done at times when praying is not allowed, and there is no difference of scholarly opinion regarding that, because the time for it is flexible, so there is no need to do it at times when prayer is not allowed. However, it is better to do it at the same time as the Eid prayer, because of what `A’ishah (may Allah be pleased with her) reported, that the Messenger of Allah (blessings and peace of Allah be upon him) went out when the edge of the disc of the sun appeared. Narrated by Abu Dawud. Moreover, it resembles the Eid prayer in the place and manner in which it is done, so it is the same with regard to time, except that the time for it does not end when the sun passes the meridian, because it is not done on a particular day, so there is no specific time for it. End quote.
An-Nawawi (may Allah have mercy on him) said in al-Majmu`, 5/77: Regarding the time for the prayer for rain, there are three views, the first of which is that its time is the same as the time of the Eid prayer…
The second view is that the beginning of its time is the same as that of the Eid prayer, and lasts until `Asr.
The third view, which is the correct view, is that there is no specific time for it; rather it is permissible and valid to offer it at any time of night or day, apart from the times when praying is disliked, according to one of two views. This is the view that was narrated from ash-Shafa`i, hence it is the view of the majority and the scholars regard it as valid. End quote.
In al-Mawsu`ah al-Fiqhiyyah, 3/308, it says: If the prayer for rain takes the form of supplication only, there is no difference of scholarly opinion regarding the fact that it may be offered at any time. But if it consists of formal prayer and supplication, then all are agreed that it is not allowed to offer it at times when prayer is disliked, and the majority are of the view that it is permissible at any time apart from the times when prayer is disliked. The difference of opinion among them has to do only with which is the best time, apart from the Malikis, who say that its time is the time of Duha, until the sun passes the meridian, and it should not be offered before or after that time. End quote.
Hence it is known that it is permissible to offer the prayer for rain after Zuhr or Maghrib or `Isha’.
And Allah knows best.