be on the crest of a wave

To be experiencing a particularly successful period. Right after I got married, I got a big promotion at work, so I'm really on the crest of a wave at the moment! The party is on the crest of a wave following the election, as they now control the White House and both houses of Congress. Those two must be on the crest of a wave after finding out, in the span of three days, that they're having a baby and that their offer on their dream house was accepted.