Question

It was too cold to step out of the house into negative sentence

Answer 1

___________________________________________________________

→ A Negative Sentence attributes Something as false !!

♦ Affirmative : "It was too cold to step out of the house"

♦ Negative : "It wasn't too cold to step out of the house" 
      ← however, that'd sound a bit ILLOGICAL with imperfect grammar

=> Correct Conversion :
     ♀ It wasn't too cold to not step out of the house ♀
___________________________________________________________

Answer 2

heya buddy! ^_<

It was too cold to step out of the house ( Affirmative).

=>It was not too cold to step out of the house ( Negative )

hope it helps! :)