The following terms are used in the Surf forecasts to describe the period length of the forecasted swell. It is important to note that these ranges were chosen to use on a global scale. So, for regions that primarily receive shorter period swells, a 12.0 second swell could be a very long swell period interval, however the ranges chosen below allow for a uniform description for all locations.

Icons of surf height and conditions are used on the Swellinfo forecast pages to give users a quick glance at the height and conditions for the morning and afternoon periods.

The Swellinfo forecast locations describe a coastline region that ranges roughly 10-40 miles. While some locations have very straight coastlines, there are many regions that vary quite a bit in the orientation of their coastlines, and thus the region’s surf height and conditions can also vary quite a bit to the exposure of a given swell. For this reason, Swellinfo has divided each forecast location into different beach facing directions of 1 to 4 primary directions. To change to a different beach facing direction, click on the direction box desired located at the top of the detailed surf forecasts.

An example: The state of Rhode Island has a very curvy coastline with lots of bends and nooks. The Rhode Island beaches vary from facing to the west (270 degrees) all the way to facing the opposite direction to the east (90 degrees). However, the primary directions of surfing beaches, which Swellinfo forecasts are generated for, are the South and East facing beaches in Rhode Island.

Swellinfo aims to create the most reliable forecasts, specific for your region. With this goal in mind, the surf forecasts are generalized for each region without attempting to capture all of the weather and oceanic variability that can occur both spatially within a forecast region (nearby spots) and temporally during a given day. To get an overall view of the variability during a forecast day, it is always best to check out the wave and weather charts. This of course, doesn’t replace the vital local knowledge that comes with experiencing the ins and outs of each surf spot, and how variables like tide, swell direction, and local wind affect each surf break. Below are a couple quick examples of the affects that spatial and temporal variability can have on surf height and conditions.

The surf might be chest height at Huntington Beach Pier, CA at noon. Meanwhile, down the road in Newport, the Wedge is serving up overhead peaks. Later that day, however, the tide changes and HB Pier starts cranking out head high waves.

The US east coast region is known for very quick moving weather systems pushing off the coast. The winds may be SW and offshore in Kitty Hawk, NC at 9:00am, but then when a cold front moves off the coast at 10:30am, the wind switches N and creates choppy, blown out conditions in Kitty Hawk. Meanwhile, a short trip down the road, in Frisco the N winds are creating clean, offshore surf.

By default, when you go to a forecast page, the wave map for that region appears in the window. To zoom out or view other region’s wave maps, use the navigation buttons in the top left corner. When you zoom in as far as possible, you can change your forecast location.

The Swellinfo swell plots are the single most useful tool when predicting the surf. Swell plots show open ocean swell heights, periods, and directions just offshore of the forecasted location. At any given time, there may be multiple swells at any location, so the swell plots split the significant wave height you see on the wave maps into the multiple concurrent open ocean swells. These concurrent swells may vary in both direction and frequency (wave height and period). Below the linear timeline of the Swell Plots is a table that shows the concurrent swell height, period, and direction at 6 hour intervals throughout the 5 day forecast. The swell plot line is matched to the color of the swell group in the data table below.

It is important to know that the open ocean swell heights do not equate to the wave face height at the beach. In order to use the swell plots to interpret how the surf will be at your local beach, it is useful to have some local knowledge to understand what makes your local breaks turn on. For example, due to the local bathymetry (or sea bottom), some spots may favor short period swells, while other breaks only come alive during longer period swells (and vice versa). In general, as the wave period increases, more energy is available to build the surf. Of course, the swell height is crucial, and the swell direction can be equally important to any spot as well.

A wave period example:

A 3ft. 7 sec. swell may only produce wave face heights around thigh or waist high at a given beach. However, if there is a 3ft, 15 sec. swell, you could easily see chest to head high surf.

The surf plots take the swell plots one step further. Where the swell plots give you the open ocean concurrent swells, the surf plots give you an idea of what that means for wave face size at the beach. It is important to note that the surf plots represent a potential wave face height for the average to better exposed breaks in a region during optimal conditions (winds,swell,tide). The surf plots are color coded to each particular swell group, which can be seen in the detailed view (same as swell plots). The summary view, gives the official swellinfo morning and afternoon forecast along with 6 hour interval forecasted winds for the primary beach facing directions at a forecast location.

The nearshore wind maps provide very high resolution(every 12km or 7.5mi) wind data that is forecasted up to 84 hours. The winds in the wave maps are a coarser resolution, and often cannot capture the microscale meteorological dynamics that can frequently affect coastal winds. That being said, the nearshore wind maps are still not able to capture all coastal wind variability (that's a beast), but are generally able to forecast signficant land/sea breeze events.

Which map should I use for winds? The wave map wind data is good to use to get a glimpse of what the winds are doing. But, it is best, especially when there are weak weather systems over your area to look at the nearshore wind maps. As with any of the forecasted data, the accurracy is most reliabe during the short term, with decreasing reliability as you go out in the future. One major advantage of the wave map winds is they are forecasted out to 180 hours. Note that sometimes during the day the starting times of the different maps may not match up and as a result the forecasted data may conflict between resources. It is always best to go with the most recently updated data. The swellinfo detailed forecasts always use the most up to date data that is available at the time of composing the forecast.

Example: In the nearshore wind map below you can see there are very light winds indicated by the dark blue color. You can also see that the winds are offshore at just about all areas along the Outer Banks. This can often happen with weak weather systems and especially in the middle of the night when air temperatures drop below the ocean temperatures (this is called a land breeze, since the winds are coming from land). The arrows point to where the wind is going, but the wind direction is expressed as where the winds are coming from. So, in the example below, at Frisco (just below the tip of the Cape), the winds are coming from the Northwest.

The ocean temperature maps are composed of very high resolution sea surfact temperature data derived from satelite and obsservation measurements. Notice in the example below, how the ocean temperature map captures the location of the Gulf Stream, which is a vital component in determining the ocean temperatures along the US East Coast.