The presence of influenza is quite rare in the spring, summer and fall, when people don't use indoor heating as much and the humidity tends to be in the comfortable 50%-to-70% range, says Dr. Marr.

WSJ: Burning Question | Why Is Flu Common in Winter?

Avalanches during the spring aren't rare, he said, noting that there's a secondary peak of landslides during this time because the Northwest still sees heavy storms, which can include snow.

NPR: Wash. Searchers Wait To Seek Avalanche Victim

For NBC, "The Voice" has been a rare success story since its debut in the spring of 2011, drawing some of the network's biggest audiences.

WSJ: 'X Factor' Producer Proposes Truce

The Blue Sox, who have enjoyed two rare successes at Odsal in the Super League era, threatened to spring another surprise when stand-off Martin Pearson put them in front after only three minutes with a penalty goal kicked from two metres inside the Bradford half.

BBC: Bulls mock Blue Sox