Water temperature plays such an important part in fishing that every angler needs to pay attention and react to even subtle variances. Fish are no different than a lot of animals when it comes to heat and cold. They want to stay comfortable. Consequently, even a small change or break will cause fish to move from one location to another.
Fishing offshore presents particular problems. Temperatures can and do change from the surface to the bottom. I have fished in water that was 80°F on the surface and below 60°F on the bottom. What appeared to be ideal water was virtually void of fish at least those that were in a feeding mood. Be aware of temperatures at varying depths and be prepared to react.
With surface temperatures, fish will often move along temperature breaks where warm and cold water meet. These breaks draw baitfish and feeding fish are close behind.
Inshore waters are not as susceptible to temperature breaks, but they do exhibit changes according to the weather. Summer water temperatures as high as 90°F absolutely turn the fish off. Winter temperatures below 50°F do the same. Sometimes in summer, daytime fishing can be fruitless when the water is that hot.
Pay attention to the NOAA weather maps online. Surface water temperatures are plotted and when cold thermoclines invade a coastline during the summer as they often do, you can see where you need to be fishing. Remember find the breaks.
Finding the Fish
Look for surface temperature breaks offshore. Pelagics like mahi mahi, king mackerel, wahoo and tuna will run these breaks. Look for median bottom temperatures in deeper water. The fish will be in a comfort zone. If its too hot or too cold, they will move to that comfort zone.
Inshore, stay with morning and evening fishing in the hot summer, and rely on mid-day fishing in the winter. Stay away from the extremes of hot and cold. There are numerous warm water discharges from power plants on almost every coast. Winter fishing around this warm water can be excellent. Conversely, summer fishing there can be the pits.
Remember look for the comfort zones and you will find the fish.