Now is the winter of our discontent, made glorious summer by this sun of York was coined by Shakespeare and put into print in Richard III, 1594. The 'sun of York' wasn't of course a comment on Yorkshire weather but on King Richard. In this play Shakespeare presents an account of Richard's character that, until the late 20th century, largely formed the popular opinion of him as a malevolent, deformed schemer. Historians now view that representation as a dramatic plot device - necessary for the villainous role that Shakespeare had allocated him. It isn't consistent with what is now known of Richard III, who in many ways showed himself to be an enlightened and forward-looking monarch.
"Now is the winter of our discontent" are the opening words of the play and lay the groundwork for the portrait of Richard as a discontented man who is unhappy in a world that hates him. Later he describes himself as "Deformed, unfinished, sent before his time into this breathing world, scarce half made up". This deformity, which has now been shown to have been exaggerated or even deliberately faked in portraits of Richard, is given as the source of his supposed evil doings. He says that as he "cannot prove a lover" he is "determined to be a villain".
The brooding malevolence that Shakespeare has Richard personify mirrors the playwright's view of the state of the English nation during the Wars of the Roses.