SwellMap user guide

SwellMap is one of the most accurate marine forecast websites in the world. Unlike many marine and surf forecast websites who provide you coarse global NOAA marine data, we take this further and deliver you with refined high-resolution data. This information captures current weather conditions using observational data and then calculates the forecast based on local features such as ocean depths and variances in the coastline like bays and headlands.

The SwellMap forecasting system has been developed by our team at MetOcean Solutions Ltd, who provide high tolerance weather data to the offshore and marine industry in New Zealand and overseas. MetOcean Solutions Ltd have been providing forecasts to the marine industry for almost 10 years. In this time they have built reliability and confidence in an industry where weather information is safety critical.

Forecasts are generated using the latest atmospheric and oceanographic numerical models, and a large computing facility. All the weather information is made in New Zealand and is presented without human interpretation. These forecasts offer specialist information for both recreational and commercial ocean users.

There are 4 main forecasts available on SwellMap:

Boating Boating, fishing, sailing etc. This type of forecast focuses on sea height and chop, with many offshore forecasts
Surfing Surfing, swimming, kayaking, windsurfing, kitesurfing etc. Most of these forecasts are just off the shoreline and focus on the quality of swell.
Forecast maps These weather maps provide a 7 day global forecast for rain (and pressure systems), temperature, wind, swell height, and swell period plus current sea temperature and a satellite view for cloud cover.
General weather Weather forecasts including summaries, rain, temperature, wind, cloud cover, humidity, pressure, and visibility

The following sections will give you an explanation of each type of forecast.

Safety Remember that all our information is a forecast. It is easy to get confused between weather reports and weather forecasts. We only provide forecasts which are the predicted conditions and not the actual conditions. It is always worth verifying the weather on the day by checking a cam or report before you go.

The forecast maps use our WXTiles technology and are a great way of viewing the weather patterns globally and locally. You can zoom and pan the map depending on the level of detail you require.

The satellite option displays the current and previous days real view of the cloud cover, and the sea temperature option is the current sea temperature. Where as the other options such as rain, wind and swell height are forecasts.

If you are not use to viewing a forecast in this format, it may initially appear difficult to interpret. However, after some practise many people prefer this view over tables and graphs. One advantage of this format is that you can watch the weather patterns like low pressure systems passing as you step through the forecast times which can help provide a bigger picture of the weather ahead.

Another example if you are interested in swell height is using the forecast maps to watch the predicted movement of new swell and how it hits the coastline. Based on the swell direction and angle of the coastline, you will be able to visualise how swell height reduces as it wraps into bays and coves.

Tip Click the icon’s or click on the “Play tour” button for help on different parts of the forecast.

Date and times provided in local time of that spot

Our forecasts provide 7 days of information which is divided up into 6 hourly blocks. The SwellMap forecasts are updated 4 times daily to keep you upto date with the latest conditions.

Ratings

Our boating ratings are designed to provide you with a quick indicator of the sea state. The rating is based on sea height and wind such that calmer conditions score more highly.

We strongly recommend that you also check the other parts of the forecast and do not solely rely on the ratings to avoid hazardous and unexpected conditions.

See the rating categories below.

Wind forecast Wind (kts)

Both wind direction and speed are important factors for boating and fishing. The wind direction on the graphs are indicated by the arrows where direction is from the origin e.g. a west wind will be moving to the east. Wind speeds for marine activities are displayed in knots. The gust speed of the wind is represented by the dotted green line.

As a general rule the stronger the wind, the rougher the sea will become especially if the wind is onshore.

Sea forecast

Sea (m) Height of the waves. This is a total of swell height and chop height.
Chop (m) Height of the ocean chop. The less, the more comfortable conditions will be.
Swell (m) Height of the swell before the wave has broken.
Swell period (s) The time between set waves. A longer period generally indicates a better quality swell. Look for jumps in the period to indicate new swells.
Swell direction ° The origin direction of the swell.
Sea direction ° The direction of the sea chop.
Info Sea sickness is more likely when swell period is less than 8 seconds and there is some chop. Also, check both the sea direction and swell direction. If they are opposing, then this could make being on a boat much more uncomfortable.

Tides

Lowest Astronomical Tide (LAT) is the height (m) above the lowest tidal water level.

Tip Click the icon’s or click on the “Play tour” button for help on different parts of the forecast.

Date and times provided in local time of that spot

Our forecasts provide 7 days of information which is divided up into 6 hourly blocks. The SwellMap forecasts are updated 4 times daily to keep you upto date with the latest conditions.

Ratings

Our surf ratings provide you with a guide on how clean the surf is likely to be based on various forecast factors such as wind direction and swell period.

Please be aware that a high rating of 10 does not necessarily mean the waves are going to be a 10 for everyone. For instance, when waves are predicted to be waist high, they can still be a 9 or 10 if the conditions are very clean. So it is worth checking the swell height and other factors to avoid unexpected conditions.

See the rating categories below.

Wind forecast Wind (kts)

Both wind direction and speed are important factors for surfing and many other water activites. The wind direction on the graphs are indicated by the arrows where direction is from the origin e.g. a west wind will be moving to the east. Wind speeds for marine activities are displayed in knots. The gust speed of the wind is represented by the dotted green line. This can be useful for windsurfing and kitesurfing when assessing the conditions as big gusts can be a problem.

Generally, winds that make good surf conditions (for most surfers) are light (less than 10 kts) or an offshore direction (for a west facing beach, an offshore wind would be moving east to west). However, there are exceptions to these rules based on the position of the spot, swell direction, and even the type of surfer. Many pro surfers like a cross shore wind for doing some of these crazy aerial manoeuvres. So some local knowledge will help you out.

Swell forecast

Set wave face (m) Predicted height of the wave face as it breaks.
Wave/sea height (m) Height of the waves. This is the swell height plus the chop height. The nearer this height is to the swell height, the less chop, meaning a cleaner swell!
Swell height (m) Height of the swell before the wave has broken.
Swell period (s) The time between set waves. A longer period generally indicates a better quality swell. Look for jumps in the period to indicate new swells.
Swell direction ° The origin direction of the swell.

Tides

Lowest Astronomical Tide (LAT) is the height (m) above the lowest tidal water level.

The general weather forecast provides you with typical forecast variables such as a summary, temperature, amount of rain, cloud cover, plus many more.

The ratings are the green, orange and red icons with a number between 1 and 10. Only boating and surfing have ratings. The ratings are a great way of getting an idea of how good the weather is for that activity at a glance. There is no need to anaylse all the different weather factors to know whether conditions are going to be good or not.

Ratings for boating

This rating is a guide to determine how pleasant the boating conditions are likely to be. But this should not be treated as a substitute for using all available sources of information for the purpose of safety.
10 A green rating between 7 and 10 indicates calm waters, based on little or no wind, and swell height less than a metre.
6 An orange rating between 4 and 6 indicates average boating conditions, possibly affected by light-fair winds, and a swell height around 1-2 metres.
1 A red rating between 1 and 3 suggests poor and possibly dangerous conditions such as strong winds and a big swell height 2-3 metres plus.
? No rating available.

Ratings for surfing

10 A green rating between 7 and 10 indicates good quality surf, based on a long swell period, little or no wind, and swell height greater than a metre. If the wind is quite strong, then it will be an offshore wind.
6 An orange rating between 4 and 6 indicates reasonable surf conditions, although possibly affected by light-fair onshore winds, and a lower swell period e.g. 8-10 seconds.
1 A red rating between 1 and 3 suggests poor conditions such as strong onshore winds, a low swell period and a small swell height, all of which can make surfing more difficult.
? No rating available.

Below are a few tips on using SwellMap.

The map is generated by Google and has the same functionality as Google Maps. Check out the Google Map navigation user guide for tips.

SwellMap should automatically display the map page for the country of your current location. If SwellMap does not have any forecasts for your country, it will find the nearest country that holds forecasts.

Before you start looking for a spot, you need to ensure SwellMap is looking at the country you require. You can set the country by selecting a country from the “Select a forecast” menu.

There are then several ways to find a surf, boating or general weather forecast.

  1. Use the “Select a forecast” menu on the left side of the page
  2. This menu allows you to select a country, select a region, and select a spot. This option is good when you want a list of the forecasts for a certain region. If you unsure of the nearest spot, it might be easier to use the map.

  3. Use the “Find a forecast” menu on the left side of the page
  4. This is quick and handy when you know the name of a spot. Just start typing and the search will predict the location you are looking for.

  5. Find your location on the map
  6. Looking on the map is great for finding new spots and understanding the geography.

It’s possible to bookmark your locations for any activity. If you look at the top of any SwellMap web page, you will see a “My Swell” menu option. This will hold all your bookmarked locations. When you want to bookmark a location, look for the “Add to My Swell” button on a detailed forecast towards the top-right corner. This will then add your location to the “My Swell” menu.

If you want to remove a bookmark, click on the relevant minus icon in the “My Swell” menu.

Warning These locations are stored as cookies in your browser. So if you delete all your cookies you will loose the “My Swell” locations you have added.