I don't think it is a tradition but I try every evening of opening day to watch the sportscenter commentators project someone hitting 324 homeruns this season because he hit 2 on opening day. Or some pitcher projecting 450 strikeouts or someone else driving in 500 runs.

The Mariners raising the 10th man flag.

On Opening Day, I put my snow shovel in the garage until next winter.

If it snows in early April - too bad.

the introduction of the teams on the field

...hearing the first crowd roar, after than I know it'll be getting warmer shortly.

The Cubs losing. :(