Relationship between median frost date and when you open your pool?


Well-known member
Nov 14, 2015
Chicagoland, IL
I haven't seen this concept specifically mentioned - just that people would ideally open when your pool approaches 60 degrees. I asked and searched for info about water temps in my area (Northern IL) and people said they open, based on temps, on average, around mid april... Which happens to coincide with the median date for frost, give or take a week. Around me, the median frost date is mid april, the last frost date is mid may.

While it makes sense to stick with the when it approaches 60, as that is very specific to the area, is it also reasonable to say to noobs like me, trying to guess when we might expect the water to reach that make, to say around the average frost date?


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Jul 16, 2012
Central MD
I'd say it's probably a reasonable date to go with. Seems like it errs on opening early versus late for your and my areas. I open then so little to no chance of algae AND because my fur swimmers don't care what the water temp is.