absolute drought vs cold spell

absolute drought

noun
  • A period of drought where there has been no precipitation for at least 15 days. 

cold spell

noun
  • A short period during which temperatures are much lower than usual. 

  • Coordinate term: dry spell 

  • A period of poor performance. 

How often have the words absolute drought and cold spell occurred in a corpus of books? (source: Google Ngram Viewer )