Tides don't rise to the same height every day. Over about two weeks they swing from big to small and back again. A few times a year they get bigger still. This guide explains why, and how to use it to plan your trips.
Spring tides
A spring tide is a tide with a bigger range than usual. Highs are higher. Lows are lower.
The name has nothing to do with the season. NOAA says spring tides "occur twice each lunar month all year long without regard to the season." The word comes from the idea of the tide "springing forth".
What causes them
Both the moon and the sun pull on the oceans. The moon's pull is stronger because it is so much closer.
At a new moon or a full moon, the sun, Earth and moon line up. The sun's pull adds to the moon's. NOAA describes the result as the oceans bulging "a bit more than usual".
So spring tides come around the new moon and the full moon. The biggest range at a given station does not always fall on the exact day of the moon phase. So we find the dates from each station's own predictions rather than from a moon calendar.
What spring tides look like on our pages
On a station page, check the "Tide range" box and the range bars in the 7-day table. When a spring tide is close, you will see a note such as "Spring tides Friday". Lows during spring tides are often minus tides, with the water dropping below 0 ft.
For example, compare the range bars on Charleston, SC across a week that includes a new or full moon. The longer bars sit around those days.
Neap tides
A neap tide is the opposite. The range is smaller than usual. Highs are a bit lower and lows are a bit higher.
NOAA explains that about seven days after a spring tide, the sun and moon are at right angles to each other. The sun's bulge partly cancels the moon's. This happens at the first quarter and third quarter moon, when the moon looks half full.
So in a normal month you get:
- Spring tides near the new moon
- Neap tides about a week later
- Spring tides again near the full moon
- Neap tides again about a week after that
Why neap tides matter
Neap tides are easy to overlook, but they are useful:
- Currents in inlets are usually gentler.
- Low tides don't drop as far, which can help at shallow ramps.
- High tides don't reach as far up the beach.
They are also the worst days for tidepooling and shelling, because less ground is uncovered.
King tides
"King tide" is a popular name for the highest tides of the year. NOAA points out that it is "a popular, non-scientific term". There is no official threshold.
What causes them
The moon's orbit is not a perfect circle. About every 28 days it reaches its closest point to Earth, called perigee. About 14 days later it is at its farthest point, called apogee.
When a new or full moon falls close to perigee, you get a perigean spring tide. NOAA says this happens "often between 6-8 times a year". These tides are higher than normal spring tides.
Seasonal effects can add to this. Along parts of the coast, mean sea level is higher at certain times of year. When those line up with a perigean spring tide, you get the tides people call king tides.
When they happen
It depends on the coast. For example, South Carolina's Department of Environmental Services published predicted king tide dates for 2026 that run from April through November, with dates in late September, October and late November.
We don't copy dates from other sites. Instead, for each station we scan a year of NOAA or CHS predictions. We take the highest 2% of high tides and group them into windows. Those windows are the king tide dates you see on our pages. It is our own simple method, and we say so on the page.
What to expect
King tides can bring water higher than usual onto beaches, marsh edges, docks and low roads. NOAA notes that perigean spring tides, together with seasonal sea level, "may cause minor coastal flooding in some low-lying areas."
Weather matters even more. Predictions only cover the moon and sun. An onshore wind or a storm on a king tide day can push water well above the forecast. NOAA warns that a storm during a perigean spring tide can make flooding "significantly worse".
If a station has a live gauge, watch the "Gauge vs forecast" figure on king tide days. It tells you if the water is already running high.
For flood warnings, follow your local National Weather Service office or, in Canada, Environment and Climate Change Canada. We don't issue flood alerts.
How to use this
For beach days and shelling
Pick spring tide days, and especially the lowest daylight low of the week. Our Best tides for fishing, shelling and tidepooling guide goes into more detail.
For fishing
Spring tides move more water, so currents are stronger. Many anglers like that. Others prefer the gentler flow of neap tides, especially from small boats or in inlets.
For boating
Plan launches and returns around the extra low water on spring tides. A ramp that works fine on neap tides can be too shallow at a spring low. Always use official charts for navigation, not this site.
Quick summary
| Tide | When | Range |
|---|---|---|
| Spring | Near new and full moon, twice a month | Larger |
| Neap | Near first and third quarter, twice a month | Smaller |
| Perigean spring | Spring tide near perigee, often 6 to 8 times a year | Larger still |
| King tide | Popular name for the year's highest tides | Largest of the year |
Check dates on any station page, for example Fort Pulaski, GA or Wrightsville Beach, NC. All tide data here is for planning only, not for navigation.