Footer placed too low on some pages

I have a problem with footer only on some pages.

I use

documentclass[a4paper,10pt]{article}
usepackage[includeheadfoot, margin=1.0cm, footskip=1cm]{geometry}
...
fancypagestyle{styleNORMAL}{
  setlength{headheight}{1.2cm} 
  setlength{textheight}{24cm} 
  ...
}

And generally, my document looks as expected.
However – on some pages, there is too much text placed and the page number at footer goes too low!
is there a way to block extending textheight? So my footer won’t go out of page? Or some different way?