Cairo is 2 hours ahead of Reykjavik
Best overlap: 8:00 AM to 4:00 PM in Reykjavik is 10:00 AM to 6:00 PM in Cairo.
The overlap falls at 8:00 AM to 4:00 PM in Reykjavik, or 10:00 AM to 6:00 PM if you're in Cairo. With 8 hours in common, treat scheduling almost as if the two cities were in the same region. The window above shifts seasonally: Cairo keeps daylight saving while Reykjavik ignores it.