What is HOT water anyway?
Seriously, the things I think about when I overthink things. Like, for Jusenkyo's sake, what is HOT water? Apparently, based on what triggers it, it isn't THAT hot.
Like, Jusnkeyo is magic and water based, so the triggers should follow the water scale, using Celsius. That means water is between 0-100 and if it used that, "HOT" water should be on the upper end, near boiling, yet, hot springs and baths worth, not even super hot ones either. Considering the recommended temp for these is 95-105 Freedom units or about 32-40 C, this is showing that Jusenkyo works on a human comfort scale rather than water.
I get it, magic, don't have to explain shit, but this means that Jusenkyo is taking living beings into account, not water, and, as such, should be using the Freedom scale since at about 95 is good enough, meaning it wants an A+ from water to change back. And we have seen cold water not needing to be near freezing, just the average pool or water used for carrying buckets is enough. And these are not THAT cold. Pools for use in schools are set to a minimum of like 77 Freedoms and usually much higher, like 85. Considering that Furinkan uses theirs and no one complains about it being freezing, they are keeping it to a good temp of like 23 C or whatever.
That means this temperature difference for triggering the curse isn't that big, as jumping from pool to jacuzzi can change it. Very human centric.
Ranma is very fortunate for that, otherwise, he would be burning himself to change back.