pleasantly cold and invigorating; "crisp clear nights and frosty mornings"; "a nipping wind"; "a nippy fall day"; "snappy weather"; (`parky' is a British term)
devoid of warmth and cordiality; expressive of unfriendliness or disdain; "a frigid greeting"; "got a frosty reception"; "a frozen look on their faces"; "a glacial handshake"; "icy stare"; "wintry smile"
If the weather is frosty, the temperature is below freezing. sharp, frosty nights
You describe the ground or an object as frosty when it is covered with frost. The street was deserted except for a cat lifting its paws off the frosty stones