Hi,
I live in central Massachusetts,
I took the cover off the other day and I lost 6 inches over the winter. I lost 6 inches last year but I had a lot of issues in the summer of 2007 as noted in my post last year in this forum. I got a lot of help in this forum and bought a DE filter which cured all of my iron issues. Last year, I found a tear on the bottom of the pool which I fixed but I probably did that scooping out all the leaves last spring.
I have a brand new winter cover and no water got into the pool over the winter and I did not siphon any pool water out of the pool. My skimmer and return were both plugged all winter.
This is not a surprise: I called 2 pool places and got different answers. One said "6 inches can be normal " and the other said "you got a leak"
2 questions)
1) What is normal evaporation over winter (Sept 1 to June 1 pool is closed)
2) Does water evaporate in the winter? .

Another thing that I do not understand: I read on the web that evaporation happens in low humidity and not high humidity which is opposite as to what I would think but it might make sense as a solar cover would raise the humidty which would slow evaporation. But the winter cover would at times raise the humidity in the pool on hot days but most days it would stay low as it is in the days of fall and spring. Sorry about the tangent.