Your crappie prefer a water temperature of 55-68 degrees in order to spawn. And as someone here has already stated, they don't all go spawn at the same time. You get your early starters and your late bloomers.

Considering water temp, length of daylight and the oncoming of the full moon, the spawn normally happens in mid-March.

With this warmer weather we're having right now, we should start seeing fish move up this week or next if it holds. Considering how cold it's been lately, we may, I would think, get a larger number of fish spawning at the same time. The usual early spawners are still waiting for the right water temperatures while the usual normal-time spawners are wondering what the heck the early spawners are so worried about. :D

The night time temps are really a key because the water will cool down at night if the air temps drop too much over night. But with the night time temps staying in the 50's recently, it should (I Hope) get them going soon or on time for the normal-time spawners.