Bass usually spawn around a full moon after the water surface temperature has reach a sustained 63° - 68° F. Because their metabolism is based on water temperature, bass will feed at lower temperatures, but generally seem to become more active when the surface temperature is above 55° F. They are very active in waters over 60° F.
Because water temperatures are affected by water clarity, location, depth and in-flowing water, you may find bass just starting to feed for the spawn on the southeast end of a lake while they may have spawned or be in the middle of the spawn in pockets on the north side of the same lake. And bass on a murky shallow water lake will probably be feeding before the bass in a deep clear water impoundment.
I had a chance to fish a power-plant lake in East Texas. Because the waters were warmed by the power plant, most of the bass actually spawned in January of the year. We were there the last week of February, the surface temperatures were from 68 to 74 degrees F, and there were beds everywhere, but only a few still had bass preparing to spawn.
If you plan your trips to lakes so you are there as they are peeking on the 60 plus degrees surface temperatures, you can actually have a month or two of pre-spawn fishing. Just be careful how you handle the old girls, and turn them loose quickly so they can finish what they are feeding for.