I have heard this expression on several occasions and came across it yesterday in a book by Margaret Atwood, The Blind Assassin, which I’m thoroughly enjoying.
You say ‘there is a nip in the air‘ when ‘the weather is cold in an unpleasant way’ (MacMillan Dictionary). Alternatively, you can say ‘it’s a bit nippy today’ or ‘the weather is nippy today’.
Some more examples, should you need them:
– As a gambit, the weather is a reassuring icebreaker for strangers on trains and in myriad, awkward lift journeys. It can be a crushingly banal conversational filler. “Hot enough for you?” might evoke the response “glorious, isn’t it?” Or “Brrrrrrr, bit nippy today,” answered by “Brass monkeys!” (BBC)
– The air over us has come all the way from Spitzbergen in the Arctic so no wonder it’s a bit nippy! (BBC)
– The sun may be shining, but there’s still a nip in the air. Slip one of these blazers over a dress or T-shirt and you’re all set for spring (The Guardian).
– Hazel was one of the first trees to recolonise Britain after the last ice age, so they can they can tolerate a nip in the air (The Guardian).
PS. There is another good expression with the word ‘nip‘, but I’ll save it for later.