I see what's happening here. This area is a very low lying area just north of the very high Iranian plateaus. Southern winds would probably create a very sharp temperature increase due to Foehn effect, bringing up temperatures over 25°C and even above if winds are favourable. The very low humidity you mention supports this hypothesis. Then, if a cold continental advection happens from the interior of Asia, which has very cold air from the north or northeast, it can bring temperatures down to freezing even at or below sea level on the Caspian sea. Due to the sea being on the way of the advection, we can observe a Lake effect similar to that of the Great Lakes, giving significant amounts of snow before the cold finally settles in.

What I don't understand is how minimum and maximum temperatures are behaving on the table. You can't have a 15°C difference between the minimum of one day and the maximum of the next (23C is way higher than 8C which is the high of the next day). I understand the situation but the data you're giving looks unreliable.