I have some temperature data like this:

The dailyHigh(f) column is a formula that I'm trying to calculate from the hourly temperature data. I'm using the Col Maximum function, but it's coming up with answers I that aren't right, like that 68 number for 2000-01-01 -- it should be 57.92, not 68. Here's the formula I'm using:

I've done this type of formula before, no clue why it isn't working here. Any ideas?
Using JMP 14.0.0 on Mac OS.