The other obvious hard-coded solution (manual unpivoting -- shown below) works too. It has more overhead but performance is still acceptable. The overhead is largely fixed and performance is barely affected by changing from one month of data to five months of data, unlike the text-parsing solutions whose timing scales roughly linearly with the number of months of data selected and quickly become impractical for larger amounts of data.

Testing twenty cold cache trials on the full set of data (still only 876 rows):

My simple solution above:
A more general unpivot solution (below):
tamerj1's solution from above:
Avg Temp (Unpivot) = 
VAR __Unpivot__ =
    UNION (
        SELECTCOLUMNS ( T, "@Time", "00:00", "@Temp", T[00:00] ),
        SELECTCOLUMNS ( T, "@Time", "00:10", "@Temp", T[00:10] ),
        SELECTCOLUMNS ( T, "@Time", "00:20", "@Temp", T[00:20] ),
        SELECTCOLUMNS ( T, "@Time", "00:30", "@Temp", T[00:30] ),
        SELECTCOLUMNS ( T, "@Time", "00:40", "@Temp", T[00:40] ),
        SELECTCOLUMNS ( T, "@Time", "00:50", "@Temp", T[00:50] ),
        SELECTCOLUMNS ( T, "@Time", "01:00", "@Temp", T[01:00] ),
        SELECTCOLUMNS ( T, "@Time", "01:10", "@Temp", T[01:10] ),
        SELECTCOLUMNS ( T, "@Time", "01:20", "@Temp", T[01:20] ),
        SELECTCOLUMNS ( T, "@Time", "01:30", "@Temp", T[01:30] ),
        SELECTCOLUMNS ( T, "@Time", "01:40", "@Temp", T[01:40] ),
        SELECTCOLUMNS ( T, "@Time", "01:50", "@Temp", T[01:50] ),
        SELECTCOLUMNS ( T, "@Time", "02:00", "@Temp", T[02:00] ),
        SELECTCOLUMNS ( T, "@Time", "02:10", "@Temp", T[02:10] ),
        SELECTCOLUMNS ( T, "@Time", "02:20", "@Temp", T[02:20] ),
        SELECTCOLUMNS ( T, "@Time", "02:30", "@Temp", T[02:30] ),
        SELECTCOLUMNS ( T, "@Time", "02:40", "@Temp", T[02:40] ),
        SELECTCOLUMNS ( T, "@Time", "02:50", "@Temp", T[02:50] ),
        SELECTCOLUMNS ( T, "@Time", "03:00", "@Temp", T[03:00] ),
        SELECTCOLUMNS ( T, "@Time", "03:10", "@Temp", T[03:10] ),
        SELECTCOLUMNS ( T, "@Time", "03:20", "@Temp", T[03:20] ),
        SELECTCOLUMNS ( T, "@Time", "03:30", "@Temp", T[03:30] ),
        SELECTCOLUMNS ( T, "@Time", "03:40", "@Temp", T[03:40] ),
        SELECTCOLUMNS ( T, "@Time", "03:50", "@Temp", T[03:50] ),
        SELECTCOLUMNS ( T, "@Time", "04:00", "@Temp", T[04:00] ),
        SELECTCOLUMNS ( T, "@Time", "04:10", "@Temp", T[04:10] ),
        SELECTCOLUMNS ( T, "@Time", "04:20", "@Temp", T[04:20] ),
        SELECTCOLUMNS ( T, "@Time", "04:30", "@Temp", T[04:30] ),
        SELECTCOLUMNS ( T, "@Time", "04:40", "@Temp", T[04:40] ),
        SELECTCOLUMNS ( T, "@Time", "04:50", "@Temp", T[04:50] ),
        SELECTCOLUMNS ( T, "@Time", "05:00", "@Temp", T[05:00] ),
        SELECTCOLUMNS ( T, "@Time", "05:10", "@Temp", T[05:10] ),
        SELECTCOLUMNS ( T, "@Time", "05:20", "@Temp", T[05:20] ),
        SELECTCOLUMNS ( T, "@Time", "05:30", "@Temp", T[05:30] ),
        SELECTCOLUMNS ( T, "@Time", "05:40", "@Temp", T[05:40] ),
        SELECTCOLUMNS ( T, "@Time", "05:50", "@Temp", T[05:50] ),
        SELECTCOLUMNS ( T, "@Time", "06:00", "@Temp", T[06:00] ),
        SELECTCOLUMNS ( T, "@Time", "06:10", "@Temp", T[06:10] ),
        SELECTCOLUMNS ( T, "@Time", "06:20", "@Temp", T[06:20] ),
        SELECTCOLUMNS ( T, "@Time", "06:30", "@Temp", T[06:30] ),
        SELECTCOLUMNS ( T, "@Time", "06:40", "@Temp", T[06:40] ),
        SELECTCOLUMNS ( T, "@Time", "06:50", "@Temp", T[06:50] ),
        SELECTCOLUMNS ( T, "@Time", "07:00", "@Temp", T[07:00] ),
        SELECTCOLUMNS ( T, "@Time", "07:10", "@Temp", T[07:10] ),
        SELECTCOLUMNS ( T, "@Time", "07:20", "@Temp", T[07:20] ),
        SELECTCOLUMNS ( T, "@Time", "07:30", "@Temp", T[07:30] ),
        SELECTCOLUMNS ( T, "@Time", "07:40", "@Temp", T[07:40] ),
        SELECTCOLUMNS ( T, "@Time", "07:50", "@Temp", T[07:50] ),
        SELECTCOLUMNS ( T, "@Time", "08:00", "@Temp", T[08:00] ),
        SELECTCOLUMNS ( T, "@Time", "08:10", "@Temp", T[08:10] ),
        SELECTCOLUMNS ( T, "@Time", "08:20", "@Temp", T[08:20] ),
        SELECTCOLUMNS ( T, "@Time", "08:30", "@Temp", T[08:30] ),
        SELECTCOLUMNS ( T, "@Time", "08:40", "@Temp", T[08:40] ),
        SELECTCOLUMNS ( T, "@Time", "08:50", "@Temp", T[08:50] ),
        SELECTCOLUMNS ( T, "@Time", "09:00", "@Temp", T[09:00] ),
        SELECTCOLUMNS ( T, "@Time", "09:10", "@Temp", T[09:10] ),
        SELECTCOLUMNS ( T, "@Time", "09:20", "@Temp", T[09:20] ),
        SELECTCOLUMNS ( T, "@Time", "09:30", "@Temp", T[09:30] ),
        SELECTCOLUMNS ( T, "@Time", "09:40", "@Temp", T[09:40] ),
        SELECTCOLUMNS ( T, "@Time", "09:50", "@Temp", T[09:50] ),
        SELECTCOLUMNS ( T, "@Time", "10:00", "@Temp", T[10:00] ),
        SELECTCOLUMNS ( T, "@Time", "10:10", "@Temp", T[10:10] ),
        SELECTCOLUMNS ( T, "@Time", "10:20", "@Temp", T[10:20] ),
        SELECTCOLUMNS ( T, "@Time", "10:30", "@Temp", T[10:30] ),
        SELECTCOLUMNS ( T, "@Time", "10:40", "@Temp", T[10:40] ),
        SELECTCOLUMNS ( T, "@Time", "10:50", "@Temp", T[10:50] ),
        SELECTCOLUMNS ( T, "@Time", "11:00", "@Temp", T[11:00] ),
        SELECTCOLUMNS ( T, "@Time", "11:10", "@Temp", T[11:10] ),
        SELECTCOLUMNS ( T, "@Time", "11:20", "@Temp", T[11:20] ),
        SELECTCOLUMNS ( T, "@Time", "11:30", "@Temp", T[11:30] ),
        SELECTCOLUMNS ( T, "@Time", "11:40", "@Temp", T[11:40] ),
        SELECTCOLUMNS ( T, "@Time", "11:50", "@Temp", T[11:50] ),
        SELECTCOLUMNS ( T, "@Time", "12:00", "@Temp", T[12:00] ),
        SELECTCOLUMNS ( T, "@Time", "12:10", "@Temp", T[12:10] ),
        SELECTCOLUMNS ( T, "@Time", "12:20", "@Temp", T[12:20] ),
        SELECTCOLUMNS ( T, "@Time", "12:30", "@Temp", T[12:30] ),
        SELECTCOLUMNS ( T, "@Time", "12:40", "@Temp", T[12:40] ),
        SELECTCOLUMNS ( T, "@Time", "12:50", "@Temp", T[12:50] ),
        SELECTCOLUMNS ( T, "@Time", "13:00", "@Temp", T[13:00] ),
        SELECTCOLUMNS ( T, "@Time", "13:10", "@Temp", T[13:10] ),
        SELECTCOLUMNS ( T, "@Time", "13:20", "@Temp", T[13:20] ),
        SELECTCOLUMNS ( T, "@Time", "13:30", "@Temp", T[13:30] ),
        SELECTCOLUMNS ( T, "@Time", "13:40", "@Temp", T[13:40] ),
        SELECTCOLUMNS ( T, "@Time", "13:50", "@Temp", T[13:50] ),
        SELECTCOLUMNS ( T, "@Time", "14:00", "@Temp", T[14:00] ),
        SELECTCOLUMNS ( T, "@Time", "14:10", "@Temp", T[14:10] ),
        SELECTCOLUMNS ( T, "@Time", "14:20", "@Temp", T[14:20] ),
        SELECTCOLUMNS ( T, "@Time", "14:30", "@Temp", T[14:30] ),
        SELECTCOLUMNS ( T, "@Time", "14:40", "@Temp", T[14:40] ),
        SELECTCOLUMNS ( T, "@Time", "14:50", "@Temp", T[14:50] ),
        SELECTCOLUMNS ( T, "@Time", "15:00", "@Temp", T[15:00] ),
        SELECTCOLUMNS ( T, "@Time", "15:10", "@Temp", T[15:10] ),
        SELECTCOLUMNS ( T, "@Time", "15:20", "@Temp", T[15:20] ),
        SELECTCOLUMNS ( T, "@Time", "15:30", "@Temp", T[15:30] ),
        SELECTCOLUMNS ( T, "@Time", "15:40", "@Temp", T[15:40] ),
        SELECTCOLUMNS ( T, "@Time", "15:50", "@Temp", T[15:50] ),
        SELECTCOLUMNS ( T, "@Time", "16:00", "@Temp", T[16:00] ),
        SELECTCOLUMNS ( T, "@Time", "16:10", "@Temp", T[16:10] ),
        SELECTCOLUMNS ( T, "@Time", "16:20", "@Temp", T[16:20] ),
        SELECTCOLUMNS ( T, "@Time", "16:30", "@Temp", T[16:30] ),
        SELECTCOLUMNS ( T, "@Time", "16:40", "@Temp", T[16:40] ),
        SELECTCOLUMNS ( T, "@Time", "16:50", "@Temp", T[16:50] ),
        SELECTCOLUMNS ( T, "@Time", "17:00", "@Temp", T[17:00] ),
        SELECTCOLUMNS ( T, "@Time", "17:10", "@Temp", T[17:10] ),
        SELECTCOLUMNS ( T, "@Time", "17:20", "@Temp", T[17:20] ),
        SELECTCOLUMNS ( T, "@Time", "17:30", "@Temp", T[17:30] ),
        SELECTCOLUMNS ( T, "@Time", "17:40", "@Temp", T[17:40] ),
        SELECTCOLUMNS ( T, "@Time", "17:50", "@Temp", T[17:50] ),
        SELECTCOLUMNS ( T, "@Time", "18:00", "@Temp", T[18:00] ),
        SELECTCOLUMNS ( T, "@Time", "18:10", "@Temp", T[18:10] ),
        SELECTCOLUMNS ( T, "@Time", "18:20", "@Temp", T[18:20] ),
        SELECTCOLUMNS ( T, "@Time", "18:30", "@Temp", T[18:30] ),
        SELECTCOLUMNS ( T, "@Time", "18:40", "@Temp", T[18:40] ),
        SELECTCOLUMNS ( T, "@Time", "18:50", "@Temp", T[18:50] ),
        SELECTCOLUMNS ( T, "@Time", "19:00", "@Temp", T[19:00] ),
        SELECTCOLUMNS ( T, "@Time", "19:10", "@Temp", T[19:10] ),
        SELECTCOLUMNS ( T, "@Time", "19:20", "@Temp", T[19:20] ),
        SELECTCOLUMNS ( T, "@Time", "19:30", "@Temp", T[19:30] ),
        SELECTCOLUMNS ( T, "@Time", "19:40", "@Temp", T[19:40] ),
        SELECTCOLUMNS ( T, "@Time", "19:50", "@Temp", T[19:50] ),
        SELECTCOLUMNS ( T, "@Time", "20:00", "@Temp", T[20:00] ),
        SELECTCOLUMNS ( T, "@Time", "20:10", "@Temp", T[20:10] ),
        SELECTCOLUMNS ( T, "@Time", "20:20", "@Temp", T[20:20] ),
        SELECTCOLUMNS ( T, "@Time", "20:30", "@Temp", T[20:30] ),
        SELECTCOLUMNS ( T, "@Time", "20:40", "@Temp", T[20:40] ),
        SELECTCOLUMNS ( T, "@Time", "20:50", "@Temp", T[20:50] ),
        SELECTCOLUMNS ( T, "@Time", "21:00", "@Temp", T[21:00] ),
        SELECTCOLUMNS ( T, "@Time", "21:10", "@Temp", T[21:10] ),
        SELECTCOLUMNS ( T, "@Time", "21:20", "@Temp", T[21:20] ),
        SELECTCOLUMNS ( T, "@Time", "21:30", "@Temp", T[21:30] ),
        SELECTCOLUMNS ( T, "@Time", "21:40", "@Temp", T[21:40] ),
        SELECTCOLUMNS ( T, "@Time", "21:50", "@Temp", T[21:50] ),
        SELECTCOLUMNS ( T, "@Time", "22:00", "@Temp", T[22:00] ),
        SELECTCOLUMNS ( T, "@Time", "22:10", "@Temp", T[22:10] ),
        SELECTCOLUMNS ( T, "@Time", "22:20", "@Temp", T[22:20] ),
        SELECTCOLUMNS ( T, "@Time", "22:30", "@Temp", T[22:30] ),
        SELECTCOLUMNS ( T, "@Time", "22:40", "@Temp", T[22:40] ),
        SELECTCOLUMNS ( T, "@Time", "22:50", "@Temp", T[22:50] ),
        SELECTCOLUMNS ( T, "@Time", "23:00", "@Temp", T[23:00] ),
        SELECTCOLUMNS ( T, "@Time", "23:10", "@Temp", T[23:10] ),
        SELECTCOLUMNS ( T, "@Time", "23:20", "@Temp", T[23:20] ),
        SELECTCOLUMNS ( T, "@Time", "23:30", "@Temp", T[23:30] ),
        SELECTCOLUMNS ( T, "@Time", "23:40", "@Temp", T[23:40] ),
        SELECTCOLUMNS ( T, "@Time", "23:50", "@Temp", T[23:50] )
    )
VAR __Result = AVERAGEX ( __Unpivot__, [@Temp] )
RETURN
    __Result
Forum Discussion

CALCULATE Challenge - Round 1

No CALCULATE Challenge -- Round #2

No CALCULATE Challenge -- Round #2b

Rounding

Qlik Sense to Power BI challenges
