Understanding Surf Conditions & Forecasts

Having a good understanding of surf conditions and how to interpret a surf forecast is key to knowing when the surf will be ideal at your local spots. This page will provide an overview of some of the conditions that will affect the waves and how to understand the information you can usually find in a surf forecast.

While the shapes and characteristics of the seafloor and shoreline will dictate what types of waves will break in a given surf spot, the weather and ocean conditions will affect how good the waves will be.

Use the information on this page to help you read the surf report for your local spots.

Swells – Height, Direction, Period

Swell is what leads to waves. Swells are created when wind and storms blow over the surface of the water and send that energy outwards.

Ground Swell vs. Wind Swell

Swells can be broken down into two main categories:

  • Windswell – defined by shorter periods or swell interval
  • Groundswell – defined by long periods or swell interval

Groundswell is the result of stronger storms moving over long distances of ocean. This type of swell often brings clean, well formed surf with consistent predictable sets.

Wind swell is created by less powerful wind and storms that occur closer to land – meaning the waves have had less distance to build energy and form clean patterns. Windswell often brings along more broken up surf.

Swell Period

Swell interval describes the time it takes for a single wave within a swell to pass a fixed position. Period/interval is measured in seconds.

Long period swells are often the result of larger storms and areas of low pressure. In a long period swell, wind can blow over a large area of ocean for a longer time picking up speed and power, and in turn create stronger, more powerful, and longer lasting waves.

Short period swell is typically the result of high pressure systems off the coast creating wind. Short period swell results in smaller, weaker, choppier surf.

Swells are further defined by their height and direction.

Swell Height

Swell height refers to the average wave height of unbroken waves traveling within a swell.

Swell Direction

Swell direction describes the direction the swell is coming from.

How well a given spot reacts to swell height and direction depends on the bathymetry of the seafloor and the direction of the shoreline.

Surf Height

The size of the waves when the reach the beach is a result of the swell height, swell period, and local conditions.

There are a few different ways to measure surf height – the main methods being measuring from the back of the wave (Hawaiian) and measuring wave face or surfable area (standard).

Most surf forecasting tools will provide wave height estimates (in feet or meters) by estimating the face of the wave.

Wave height can also be described in relation to an average-sized surfer’s body:

  • 1-2ft = Ankle to Knee high surf
  • 2-3ft = Thigh to Waist high surf
  • 3-4ft = Shoulder to Chest high surf
  • 5-6ft+= Head high + surf

Obviously, not every wave that comes through is going to be identical. You’ll typically have some bigger waves, smaller waves, and sets of waves come through at different times depending on the swell and conditions.

Wind – Speed & Direction

Wind speed and direction is going to have a big effect on the overall surf conditions.

Depending on the strength and direction, wind affects how a wave breaks, the texture of the ocean surface, and the temperature of the air and water.

No wind or very light wind will result in glassy conditions in which the wave’s surface is smooth.

Wind direction, like swell direction, is described as where the wind is coming from. With the direction and shoreline in mind, winds can be described as:

  • Off-shore: Offshore winds blow from the land out towards the ocean. These can help groom the surface of a wave and help is stand up and barrel. Very strong offshore wind can make paddling into a wave more difficult.
  • Onshore: Onshore wind blows from the sea towards the shore. Onshore winds can often have a choppy and sloppy effect on the surf causing waves to crumble and wind chop to form.
  • Cross-shore: Cross-shore wind describes wind coming in from an angle. It can be more onshore or off-shore and may positively or negatively affect the surf depending on the location.

Depending on the exact spot and local topography and environment, you may find some shelter from certain wind directions. Wind shelter or protection could come in the form of sea cliffs, man-made structures, canyons, etc. and can work to dull or amplify the effects of the wind.


Tides are another thing to consider when checking the surf.

Everyday, the ocean cycles through different tides.

Depending on your location, the heights of the tides will vary throughout the day.

The height of the tide combines with the characteristics of the seafloor to influence how the surf will be. You’ll find that some spots work better on a low tide, some on a high tide, and some on a mid tide. Furthermore, you may find some spots work better when the tide is outgoing or incoming. Or, you might find some spots that are mostly unaffected by the tide.

You can start to explore some of the ideal conditions for spots near you using the Wave Arcade Surf Spot Directory and Forecast Comparison pages.

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