From the book "Trolling Truths" by Sep Hendrickson...
Generally, the period three days before a new moon and up to seven days afterward seems to produce the best action. We try to plan our trips accordingly with the use of a moon-phase calendar. To the contrary however, we have had phenomenal fishing success during bright moon periods. How do you figure? Overall, there is certainly a correlation between a new moon and good fishing, but these periods too, are affected by fluctuating barometric pressure conditions. Certainly, variables such as these, plus cloudy skies and wind, have to be dealt with. Alone, or in combination, each will have an impact on angling success.
The single most important factor deciding the fate of a day of fishing, is the CHANGE IN BAROMETRIC PRESSURE. Rapidly changing barometric pressure often puts fish off the bite. Dropping barometric pressure signals a weather change or the arrival of a storm front. Rising pressure indicates the onset of high pressure or clearing weather. Let the pressure settle down and stabilize for a couple days in a row, and angling becomes far more productive.