All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.
Allaah determined a fixed time for the performance of the five daily prayers. Therefore, in principle, it is not permissible to perform any prayer earlier than its prescribed time or delay it without a sound reason, like traveling, being in a state of fear, in case of rain, hardship, difficulty, sickness and the like. Allaah Says (what means): {Indeed, prayer has been decreed upon the believers a decree of specified times.} [Quran 4:103]
Furthermore, the Prophet clarified the beginning and the ending of the time of each prayer. Therefore, if a person performs a prayer before its time begins, then this prayer is not sufficient for him and he is obliged to repeat it after its fixed time begins. For example, the scholars unanimously agreed (without any difference of opinion) that the time of the ‘Ishaa’ prayer begins when the red twilight disappears .
If, in any country, the red twilight is delayed even until after midnight, then the Muslims in such country are obliged to perform the prayer on its specific time as long as this juristic time is evident to them.
Moreover, it is not permissible for the people of that country to combine the Maghrib and ‘Ishaa’ prayers because the delay of the disappearance of the red twilight or because the night is too short, as this is not an Islamically legal reason for combining the prayers.
Allaah Knows best.