Answer
(Fatwa: 1022/947=D/1429)
The time of Isha salah starts when shafaq (twilight) disappears after the sunset. The duration between the sunset and disappearing of shafaq is different on account of weather and place; sometimes at the same place this duration differs in different seasons. However, the places where shafaq disappears just after sunset because of which the time of Isha salah is untraced, then the people over there should offer Isha salah after a normal break (after Maghrib salah) as they used to do in normal days of the year. In the Hadith-e Dajjal, we have been asked to estimate the time, from which the ruling of such situation will be derived. (Hadith-e-Dajjal, Tirmizi 2:48)
Allah (Subhana Wa Ta’ala) knows Best
Darul Ifta,
Darul Uloom Deoband