There are many things in nature that have a direct effect on fishing. At this time of year one of the biggest is changing weather patterns that can change during a single day.
During the winter months the weather can go from springlike back to winter in a hurry. This causes a big change in feeding and locations of most fish during the wintertime.
Fish like smallmouth bass, crappie, trout and some others will feed during most of the winter, but the more stable the weather is over a longer period of time the better the fishing will be.
When the weather or temperatures take a big dive, the fishing will slow in the shallow areas and will move most fish to deeper more stable areas till things settle down.
When you are fishing during this time, use smaller, slower baits for the best action. Natural colors seem to work best fishing slow.
Be safe and fish when you can.