In reply to a post by camieabz:

Bibles? F1

Excel Bible

Not sure what your F1 reference is to [confused

Open Excel and hit F1.

Doh! And there's me thinking motor racing

And to quote from the Help

You cannot use the AND and OR functions in array formulas directly because those functions return a single result, either TRUE or FALSE, and array functions require arrays of results. You can work around the problem by using the logic shown in the previous formula. In other words, you perform math operations, such as addition or multiplication, on values that meet the OR or AND condition.

Nevertheless I still like paper books so that I can browse without having to stare at a screen. Ok, so call me old-fashioned

A bit of playing around has given me another 2 ways (albeit both much the same) to achieve the same result without using nested IFs.

The original formula was
=COUNT(IF(YEAR(Dates)=YEAR(J$39),IF(MONTH(Dates)=MONTH(J$39),IF(DegreesF>$AH42,IF(DegreesF<$AH43,1)))))

the first alternative is
=SUMPRODUCT((YEAR(Dates)=YEAR(J$39))*(MONTH(Dates)=MONTH(J$39))*(DegreesF>$AH42)*(DegreesF<$AH43))

and a slight variation, entered as an array formula, is
=SUM((YEAR(Dates)=YEAR(J$39))*(MONTH(Dates)=MONTH(J$39))*(DegreesF>$AH42)*(DegreesF<$AH43))

I imagine an experienced pivot table user would get the desired info far quicker. Pivot tables are not my thing, but it seems to be a PT scenario.