Solunar theory explained

Solunar theory holds that fish and game are most active around the moon’s daily passages, and that the new and full moon bring the strongest feeding of the month. It splits each day into major and minor periods, the windows when activity is most likely to peak. It is a planning aid, not a guarantee, but many anglers find it lines up with their best days.

Major and minor periods

There are two major periods and two minor periods a day, set by the moon’s position:

• Major periods center on the moon’s transit, when it is highest overhead, and its opposite, when it is directly underfoot on the far side of the earth. Each lasts roughly two hours.
• Minor periods center on moonrise and moonset, and each lasts about an hour.

The idea is that the moon’s pull, like the tide it drives, cues feeding. The overhead and underfoot passages are the strongest cues, which is why the majors are longer and weighted more.

The moon phase

The new and full moon are considered the best days of the month, because the sun and moon align and their combined pull is strongest. The first and last quarter are the weakest. Slackwater computes a daily bite rating that peaks near the new and full moon and eases toward the quarters, so you can see at a glance which days are worth the early start.

Using it with the tide

Solunar windows are most useful alongside the tide, not instead of it. A major period that lands on a moving tide, near dawn or dusk, is a strong combination. Slackwater shows the solunar windows and the tide curve together for your spot, so you can find where they overlap.

An honest note

Solunar timing is a heuristic. Weather, water temperature, bait, and pressure all matter, and no theory beats time on the water. Treat the rating as one more input, and keep your own log of what worked. Learn more in our guide to reading a tide chart, or browse tide times by location.