I used to think so too, but recently in a conversation with one of the most successful big bass fishermen who has ever lived, Mike Long, I asked about spawning temps for bass. Mike insisted that water temp has very little if anything to do with it. Rather, length of day / time of year, coinciding with a full moon makes all the difference !
I know there a lot of guys who are just blowing smoke, but when a guy has caught dozens of bass over 15 lbs, (3 16's and 2 18's in just the last 5 weeks !!!) I tend to pay very close attention to what he is saying !

Some points to ponder,
Fish Chris