Solunar theory: major and minor fishing periods

Where solunar theory comes from

“Solunar” blends sun and lunar. The theory was put together by John Alden Knight, an American angler and outdoor writer. He began with something plenty of anglers and hunters had already noticed: there are stretches when everything seems to wake up at once, and stretches when nothing moves, even when the weather hasn’t changed.

Knight looked for what those active stretches had in common and settled on the moon as the key. In 1936 he published his first solunar tables, listing the active times for each day. Versions of them have run in outdoor magazines, almanacs and fishing apps ever since.

The core idea is simple: if the moon moves the ocean through the tides, maybe it also sets the rhythm of feeding, even in lakes and ponds where the tide is too small to notice.

Major and minor periods

Every day, the moon passes four key points. Two of them mark the major periods and two mark the minor periods:

• Upper transit: the moon crosses your local meridian, the imaginary north-south line that runs directly overhead. It’s the moon’s highest point in the sky. This centers a major period.
• Lower transit: about 12 hours and 25 minutes later, the moon crosses that same meridian on the far side of the Earth, directly underfoot. You can’t see it, but the theory treats it much like the overhead pass. This centers the other major period.
• Moonrise: the moment the moon clears the horizon. This centers a minor period.
• Moonset: the moment it drops below the horizon. This centers the other minor period.

Major periods run about two hours: an hour before and an hour after the transit. Minor periods run about an hour: 30 minutes before and 30 minutes after moonrise or moonset. Keep in mind that the moon rises and sets at all hours, including in broad daylight, so a period can land at noon or at 3 a.m.

Some days are missing a period. Because the lunar day is a little longer than 24 hours, every so often moonrise or moonset skips a calendar day, and that day has only three periods.

Why the times change every day

The moon returns to the same spot in the sky about every 24 hours and 50 minutes. That’s the lunar day, the same clock the tides run on, as we explain in what causes tides.

In practice:

• each solunar period arrives about 50 minutes later than it did the day before;
• a major period that falls in the early afternoon today will fall in the late afternoon two or three days from now;
• in about two weeks, the periods work their way around the clock and land near the same times again.

So there’s no point memorizing “the good hour” for your spot. You have to check it every day.

Good days and slow days

Knight didn’t rate every day the same. According to his theory, activity runs higher:

• near the new moon and the full moon, which are also spring tide days, with stronger currents and more water moving (see our guide to spring and neap tides);
• when a period overlaps sunrise or sunset, the hours when many fish are already more active because of the light.

That’s how TidePlanet calculates it for every place: major periods run from an hour before to an hour after each lunar transit, and minor periods from 30 minutes before to 30 minutes after moonrise and moonset. The day’s activity rating (low, medium or high) goes up near the new and full moon and when a period lines up with sunrise or sunset.

An example with real times

Picture a late-September day at the full moon in Charleston, South Carolina. The sun and moon times are close to the real ones for that kind of day; the tides are an example:

Event	Time	Period
Moonset	7:00 a.m.	Minor, 6:30 to 7:30 a.m.
Sunrise	7:10 a.m.	—
Moon underfoot	1:05 p.m.	Major, 12:05 to 2:05 p.m.
Moonrise	7:05 p.m.	Minor, 6:35 to 7:35 p.m.
Sunset	7:10 p.m.	—
Moon overhead	1:35 a.m. (next night)	Major, 12:35 to 2:35 a.m.

By the theory, it’s a strong day: full moon, and both minor periods fall right at dawn and dusk.

Now add the tide. Say low tide is at 6:40 a.m. and high tide at 1:00 p.m. The water starts flooding just as the dawn minor period gets going, which is when redfish often follow the water up the marsh edges and onto the flats to feed. That morning window, from first light to about 9 a.m., has almost everything going for it: rising water, low light and a solunar period.

The midday major period, on the other hand, lines up with high slack under a bright sun. In clear, shallow water, that may well be the slowest stretch of the day, whatever the table says. And if the evening minor period coincides with low slack around 7:15 p.m., don’t expect much until the water starts moving again.

What the research says (and doesn’t)

Solunar theory isn’t proven. Studies that have put it to the test, in saltwater and in lakes, report mixed results: some find a weak link with the moon and others find none. None has shown a strong effect that holds for every species and every place.

It’s also hard to test. Fish activity depends on many things at once: water temperature, season, light, wind, barometric pressure, water clarity and, on the coast, above all the tide. Pulling the moon’s effect out of all that takes a lot of data.

What is certain is that the moon drives the tides, and the tides move fish along the coast. In saltwater, some of what gets credited to the solunar table may really be the current.

How to use it without becoming a slave to the table

A sensible order for deciding when to go:

1. The tide. On the coast, moving water usually matters more than anything else. Find the stage of the tide that works best at your spot.
2. The light. Dawn and dusk are hard to beat, especially in summer and in clear water.
3. The weather. Wind, swell, a falling or rising barometer and rain can wreck the best day on the table.
4. The season. If the fish you’re after haven’t shown up yet, no solunar period will bring them.
5. Solunar times, as a tiebreaker. If you have two similar windows, pick the one with a period in it, ideally a major.

And if you can only fish at one particular time, check whether a period falls inside it and make the most of it. It costs you nothing.

Taking it to the water

• Check the times every day: the periods slide about 50 minutes from one day to the next.
• Give more weight to days near the new and full moon, and to periods that land at dawn or dusk.
• Combine solunar times with the tide and the light. On their own, they say little.
• Keep a log. After a few seasons, you’ll know whether it works where you fish.

To see what else changes with each phase of the moon, read our guide to moon phases and fishing.