you probably want to use the AVERAGEIFS() function, or you could use the AVERAGE() function in an array formula, or you could use a good old fashioned SUMPRODUCT()....the sumproduct is my formula of choice.
so column A has the time...
you dont mention what column your dates are in...i will guess column B has January 1 2019 to January 31 2019 all listed out.
so your formula in C1 would be
=SUMPRODUCT(((A1:A31)>0)* (A1:A31)* (WEEKDAY(B1:B31, 2)<6))/SUMPRODUCT(((A1:A31)>0) *(WEEKDAY(B1:B31, 2)<6))
it should just work with a copy&paste, but let me know
in that case, open a new blank sheet, and make a simple test of 5 rows (easy to calculate an average
- A1 to A5 gets 5 times
- B1 to B5 gets 5 dates ( you can format the dates to show just the day
then try the formula
change the dates randomly to test it out.
once you get it working....then in your real sheet, just flip the columns in the formula...