Guide
Reading a south coast tide table
Checked September 11, 2026 against NOAA Tides and Currents, the Oregon Department of Fish and Wildlife (ODFW) and the Oregon King Tides Project.
The Tides tile shows NOAA’s predictions for ten stations from Reedsport to Brookings. Here is what the heights are measured from, why two places on one bay give different times, and when the table will be wrong.
A tide table is a prediction, not an observation. NOAA predicts only the tide the moon and sun make. It says it cannot predict what wind, rain, freshwater runoff and other short-term weather will do, and its predictions leave out storm surge. A storm or a river in flood will beat the table.
Heights are measured from MLLW
Every height on the tile is in feet above mean lower low water (MLLW). Most days on this coast have two low tides, one lower than the other. MLLW is the average height of the lower of the two, taken over NOAA’s 19-year reference period. It is the zero on U.S. nautical charts and in NOAA’s predictions.
So 0.0 ft is not the lowest the water goes. It is an average low. A low tide that drops below that average prints as a negative number, such as −1.2 ft: a minus tide.
Minus tides and clamming
The lower the tide, the more beach and tideflat is uncovered. ODFW says the best clamming is on low and minus tides, and for razor clams to be on the beach about two hours before the low. Before you dig, check the shellfish closures and call the ODA hotline, 1-800-448-2474. The tide table says when you can dig, not whether you may.
Why times differ up the bay and the rivers
NOAA makes predictions two ways. A harmonic station has enough years of measurements that its tide is calculated directly. A subordinate station had only a short-term gauge, so NOAA takes the high and low tides at a nearby reference station and shifts them by a set time and height.
Coos Bay shows why it matters. NOAA predicts both Empire and the Coos Bay waterfront from the Charleston gauge near the bay entrance. High tide at Empire comes about 40 minutes after Charleston, and at the Coos Bay waterfront about an hour and a half after, and both rise a little less. The tile gives each station its own row, and puts the ones up the bay and the rivers behind a fold, for that reason. Use the station nearest to where you will be standing.
Subordinate stations give high and low times only. Anything between them, including the curve on the tile, is an estimate.
King tides
“King tide” is not a scientific term; NOAA calls it a popular name for exceptionally high tides. In Oregon they come in early winter, when the moon is closest to the Earth and the Earth closest to the sun. They are in the predictions like any other tide. What the predictions do not include is a storm on top of one. The Oregon King Tides Project, run by CoastWatch and the Oregon Coastal Management Program, publishes each winter’s dates and asks people to photograph how far the water reaches.
Checking what the water is doing
Two of the stations on the tile have live NOAA gauges that report what the water is actually doing: Charleston and Port Orford. Compare the measured level with the predicted one to see how far off the table is running today.
Sources
- NOAA Tides and Currents (the predictions the board reads)
- NOAA, tidal datums (MLLW)
- NOAA, tide predictions help and tide predictions user guide (harmonic and subordinate stations)
- NOAA Tides and Currents, frequently asked questions (weather and predictions)
- NOAA predictions for Empire and Coos Bay, both predicted from Charleston (NOAA’s time and height offsets: Empire, Coos Bay)
- NOAA Ocean Service, what is a king tide?
- Oregon Coastal Management Program, citizen science the Oregon King Tides Project, and CoastWatch, King Tides
- ODFW, clams and how to razor clam