Deadeye is on the spot. I think they all contribute but I feel the most important is daylight hours is the most important. I read an article a couple years back the backed up with several years of data the correlation between daylight hours and the crappie spawn. I believe it was 12 hours? When the days get that long it was on! Now heavy rains, rising waters, and artic fronts could shut them down..... but I just don't believe they will start regardless of water temp until the days get right. Just my opinion.