Interesting. I'm near Sarasota on FL's west coast. The nearest towns in the table are Tampa and Ft Myers. Taking an average between those two, I come up with a difference of 1.9% RH between the high and low over the year. However, since this table will be in an air conditioned and heated house and the table will have a finish on it, those numbers will be different. I have two temperature/humidity gauges, one in the house and one in my garage shop. Each displays the high and low for the day. Unfortunately, it doesn't retain that info for more than a day. I think I'll set up a spreadsheet and record those daily readings. It will take a year but I'll end up with accurate information. I can also make note of any out of the ordinary occurrences, like hurricanes, which can have an impact on the numbers. I also have a large clock with temp and humidity in the lanai. I can get outside readings from it. Thanks for fostering the idea. I'll post the results next year.