If I say I'll be at a place come rain or shine, I mean that I can be relied on to turn up; nothing, not even the vagaries of British weather, will deter me or stop me from being there.
People sometimes say that every cloud has a silver lining to comfort somebody who's having problems. They mean that it is always possible to get something positive out of a situation, no matter how unpleasant, difficult or even painful it might seem.
To say that something has been enjoyable or successful, you can say that it has gone down a storm. Eg. Last night's party went down a storm, it was incredible.
The silly season is midsummer when Parliament is closed and nothing much is happening that is newsworthy, which reduces the press to reporting trivial and stupid stories.