IF statement that changes based on met condition

In cell J3 enter the formula =INDEX(C:C,MATCH(INT(I3),B:B,0)) and copy down.

To understand the formula, work inside out:

1. INT(x) returns minute 1 given minute 1.033
2. MATCH(INT(x),B:B,0) finds the row in column B in which minute 1 appears
3. INDEX(C:C,MATCH(INT(x),B:B,0)) picks the temperature in column C corresponding to that row in column B

If I understand you properly, this is simply called "nesting."

An IF statement in Excel is =IF(TRUE,DO IF TRUE, DO IF FALSE) and so you simply insert another full IF statement as one of the branches. You can put the IF statement in either (or both) decision branch.

Again, if I have followed your question, you can start with the least likely or last condition, and then nest additional tests in reverse order. It sometimes helps to write it out using notepad or something and then collapse the spacing to fit as a formula (this is pseudocode to hopefully help illustrate the idea better):

=IF(Field = COL3, UseCOL3, 
    IF(Field = COL2, UseCOL2,
        IF(Field = COL1, UseCOL1,
            NoValue
        )
    )
)

Or:

=IF(Field = COL3, UseCOL3,IF(Field = COL2, UseCOL2,IF(Field = COL1, UseCOL1,NoValue)))

It can get "hairy" very quickly.

https://support.microsoft.com/en-us/office/if-function-%E2%80%93-nested-formulas-and-avoiding-pitfalls-0b22ff44-f149-44ba-aeb5-4ef99da241c8