Dex wrote about jewish and islamic dieatary laws in the article:
I’ve had a discussion here in Finland with several muslim friends about following Ramadan beyond arctic circle. The problem lies that if Ramadan falls on mid summer the sun never sets and during mid winter it never rises. The concensus that my muslim friends came up is that one should follow Meccas sun rise and set times in this case. How widely followed ruling this is I don’t know, but it makes sense.