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Tides, swell and water temperature

Where to find the next high and low, the 48-hour tide curve, wave height and period, the water temperature and the day's light, and which stations they come from.

iPhone and AndroidHomeConditionsUpdated September 4, 2026

Also known as: tide, tides, high tide, low tide, tide chart, tide times, when is high tide, swell, waves, wave height, period, sea state, chop, water temperature, sea temp, sunrise, sunset, first light, last light, daylight

Tides and swell share the Conditions tab with the wind, and each has a tile in the Now row on Home. Both come from live NOAA stations near Marina del Rey, with a forecast model filling in the hours ahead.

The quick read on Home

In the Now row on Home, the Next High or Next Low tile shows the next turn of the tide with its height and time, the Swell tile shows the wave height with the period in seconds and the direction the swell is coming from, and the Water tile shows the sea temperature. Tap any of them to jump to the matching block on Conditions.

Swell & Waves

  1. Open the Conditions tab and scroll to Swell & Waves, or tap the Swell tile on Home.

    The Swell & Waves block with the height, period, compass and 24 hour chart

  2. The large number is the significant wave height right now, with the period and the direction the swell comes from beneath it. The compass shows that direction as an arrow.

  3. The chart covers the next 24 hours of wave height. Drag a finger across it to read a particular hour; the big number follows your finger and returns to now when you lift it.

The source line at the top right of the block says NDBC 46221 when the number is a live reading from the Santa Monica Bay wave buoy, and Open-Meteo when it is the model’s forecast. The buoy sits about 11 nautical miles out in the bay, so it feels the open swell; inside the breakwater and in the basins the water is far calmer than the number suggests, and outside the entrance on a west swell it can be lumpier than the chart.

Tides

  1. On the Conditions tab, scroll to Tides · Next 48 hours, or tap the tide tile on Home.

    The Tides block with the 48 hour curve and the high and low cards

  2. The curve is the predicted water level over the next two days. The faintly tinted bands are the daylight hours, so you can see at a glance whether a low falls in the dark.

  3. Under the curve, one card per turn lists High or Low with the height and the time. An arrow pointing up marks a high, pointing down a low.

Heights are from NOAA’s tide station at the Santa Monica pier (CO-OPS 9410840), the reference station for the bay, and are measured from mean lower low water, the same datum your chart uses. Marina del Rey has no tide station of its own; the pier is 3.8 nautical miles up the coast, close enough that the times are the same for practical purposes.

Water temperature

The Water tile on Home and the Weather block on Conditions both show the sea temperature, read from the Santa Monica station.

Daylight

The Daylight row on Home with first light, sunrise, sunset and last light

Further down Home, the Daylight row gives First light, Sunrise, Sunset and Last light for today at the harbor. First and last light are civil twilight, when the sun is six degrees below the horizon and there is still enough light to see by. The briefing uses the same times when it tells you how much daylight is left.

Units

Heights show in feet or metres and temperatures in Fahrenheit or Celsius. Change either in Profile under Units & Display.

Still stuck? In the app, open Profile, then Help & Support, and use Send to support. Otherwise email support@slipside.app.