So if its a very cold day you could say on an extremely cold day.or if its not so cold you could say on a slightly cold day. Hope this helps.

Hi, What you need to ask yourself is if the day is 'little' or the cold is 'little'. Little and cold are both adjectives, so they are both describing the day. That sounds a bit strange - how can a day be little? If you want to say that it was not very cold, you need to use an adverb to modify cold. As someone else has suggested, 'slightly' would be a good adverb to use, but you could also use 'mildly'. I hope that helps!

Hi. Surely, you can use other expressions, but it is definitely correct.

You need to give the whole sentence for us to tell, but it's probably not correct. "A little cold day" sounds like the day is little and cold.