CarterTC wrote...
I have 22 columns consisting of about 5500 rows aligned by date with
each column containing hourly temperatures for a different subject over
a several month period. *I need to determine the percentage of hourly
records that fall above a particular upper temperature limit (26 degrees
C in this case) every 7 days for each of the 22 subjects.
....

So each column is a different subject? Hourly temperatures means 168
cells per 7 day period?

Do you need the percentages of temperatures above 26C separately for
each week? I'll assume so. Further, I'll assume the data is in
C3:X5002.

C5004:
=COUNTIF(INDEX(C$3:C$5002,168*ROWS(C$5004:C5004)-167):INDEX(C$3:C
$5002,168*ROWS(C$5004:C5004)),
"26")/168

Fill C5004 right into D5004:X5004. Select C5004:X5004 and fill down as
far as needed. Format these cells as %.