A tide chart shows how high the water will be through the day. A tide table lists the same thing as times and heights. Once you know the parts, planning a beach day takes a minute.
This guide uses our station pages as examples. Open one in another tab, such as Myrtle Beach, Springmaid Pier, and follow along.
The tide table: four lines a day
Most tide tables list each high and low tide with a time and a height. On the US East Coast you will usually see four lines a day: two highs and two lows.
A made-up example looks like this:
| Tide | Time | Height |
|---|---|---|
| Low | 2:31 AM | 0.3 ft |
| High | 8:44 AM | 5.4 ft |
| Low | 2:47 PM | 0.6 ft |
| High | 9:02 PM | 5.9 ft |
Read it top to bottom. The water is lowest at 2:31 AM. It then rises for about six hours to the morning high. It falls again to the afternoon low, then rises to the evening high.
Some days only show three lines. That is normal. Tides run on a lunar day of about 24 hours and 50 minutes, according to NOAA. So each tide comes roughly 50 minutes later than the day before, and one of the four can slip past midnight into the next date.
Not every coast gets two highs
NOAA describes three basic patterns:
- Semidiurnal: two highs and two lows a day, of about the same height. Common on the East Coast.
- Mixed: two highs and two lows, but of clearly different heights. Common on the West Coast.
- Diurnal: one high and one low a day. Found in parts of the Gulf of Mexico.
Each of our station pages tells you which pattern that station has, based on a month of predictions. On a mixed tide, pay attention to which low is the lower one. It can make a big difference for tidepools.
The tide chart: a curve over the day
The chart draws the table as a smooth line. Time runs left to right, from midnight to midnight. Height runs bottom to top.
On our charts:
- The blue line is the prediction.
- The amber line is what a live gauge has measured so far today, where the station has one.
- The amber vertical line marks the current time.
- Grey shading marks night, from sunset to sunrise.
- Labels at each peak and dip give the exact time and height.
The steepest part of the curve is when the water moves fastest. That is usually around mid tide, halfway between a high and a low. Near the top and bottom the line flattens. That flat part is often called slack water, when the level barely changes.
What the heights mean
A height of 5.4 ft does not mean the water is 5.4 feet deep. It means the water is 5.4 feet above a reference line called the datum.
In the US, NOAA uses Mean Lower Low Water (MLLW). That is the average of the lower low tide each day over a 19-year period. So 0 ft is roughly a normal low tide.
In Canada, the Canadian Hydrographic Service uses chart datum, which is set lower. We explain both in What MLLW and chart datum mean.
Minus tides
Sometimes a low tide shows a negative number, like -0.2 ft. This is a minus tide. The water has dropped below the datum line, so more beach, mud or rock is uncovered than on a normal low.
Minus tides tend to come around the new and full moon. These are good days for tidepools and shelling. See Spring and neap tides, and king tides for why.
The tide range
The range is the difference between a high and the low next to it. In our example, the evening high of 5.9 ft minus the afternoon low of 0.6 ft gives a range of 5.3 ft.
A bigger range means:
- Water moves faster between high and low.
- More ground is covered and uncovered.
- Currents in inlets are usually stronger.
Our 7-day table shows the daily range as a bar, so you can spot the big days quickly. Georgia, for example, has larger ranges than much of the Southeast coast. Compare Fort Pulaski, GA with Myrtle Beach.
Predicted vs measured
A tide prediction is a forecast based on the moon and sun. NOAA is clear that it cannot predict the effect of wind, rain, river flow and other weather. In Chesapeake Bay, NOAA says wind has pushed water 1 to 2 feet above or below the predicted tide.
That is why we show the live gauge where one exists. NOAA gauges report every 6 minutes. On a station page, the "Gauge vs forecast" box tells you how far the water is running above or below the prediction right now. If it says +0.4 ft, expect the next high to come in about that much higher than the table, as long as the weather holds.
Times near you may differ
A tide station is a single point. A beach 5 miles away can see the tide turn earlier or later. Inside rivers and marshes the delay can be large.
Some stations are "subordinate". NOAA does not run a full model there. It predicts them by adding time and height corrections to a nearby reference station. These are fine for planning, but only the high and low times are official. We draw the curve between them.
Our "Nearby stations" list shows how many minutes earlier or later each nearby station's high tide comes. Pick the one closest to where you will actually be. Near Wilmington, NC, for example, Wrightsville Beach and Wilmington on the Cape Fear River can differ a lot.
A quick checklist
- Find the station nearest to your spot.
- Note the time and height of the tide you care about.
- Check the gauge and the wind.
- Allow for local differences.
Tide times on this site are for planning only. They are not for navigation.