Beach forecast and tide times explained

Beach forecast explained

1. What is the beach forecast?

The beach forecast is a 5 day forecast specific to the chosen beach. For each day we supply the beach weather conditions, sea temperature, an estimate of the surf height and offshore wave conditions. Read on to find out more about each of the types of information provided. You can use the forecast to get an idea of the conditions on the beach itself and in the water for those looking to swim or surf.

We provide beach forecasts for around 490 beaches in the UK.

2. Understanding the beach forecast

Wind direction

The wind direction graphic indicates where the wind is blowing in relation to the positioning of the beach. The blue illustrates the sea, with the green representing the position of the land. You can therefore determine whether the wind will be blowing in from the sea (onshore), going out to sea (offshore wind), or blowing across the length of the beach (cross-shore). Offshore winds can be potentially hazardous to users of inflatables, stand-up paddleboards and kayaks. Be sure to seek advice from lifeguards if in doubt about what to do in these conditions.

Height of waves offshore

The offshore wave forecast information represents wave conditions in open waters (10-30m depth) several kilometres offshore of the beach. These values approximate the average height of the highest one-third of waves. This is one of the most accurate forecasts of its type for the UK and provides key information for our surf height forecasts.

The difference between the expected surf height and height of waves offshore is determined by three things:

  1. How much of the offshore wave energy is likely to be headed towards the beach (a function of wave direction offshore, the direction the beach faces and how sheltered the beach is)
  2. The wave period (longer period waves will increase the surf height)
  3. The beach slope (waves will break more rapidly and energetically on beaches with steep slopes)

Period of waves offshore

The period of waves offshore refers to the period of the most energetic waves and how long, in seconds, there is between the peak of one wave and the next.

Direction of waves offshore

Wave directions are the direction from which the waves come and are displayed relative to the direction faced by the beach in the box graphic. The reason for presenting beach and wave direction together is that you can more easily see when the majority of wave energy is likely to directed toward the beach or parallel to/away from it; this is one of the key factors that influences the breaking wave height forecasts. Beach orientation will be constant for a given beach site forecast, but may well vary from beach to beach within an area, or across different regions.

If you would like more information on how to read the weather forecast shown above the beach forecast information, read our guide on how to understand a forecast. You can also find more beach safety advice from the RNLI here.

Tide times explained

1. What are tides?

Tides refer to the rise and fall of a body of water, most commonly seen in the oceans; caused by the interaction between the Moon, Sun and Earth.

As the positions of Earth, Sun and Moon change in relation to each other, gravitational forces acting upon the oceans vary and it is these differences that cause fluctuations in the height of the sea. These changes in water level are often strongest at the coastline and, on a beach, can be seen as the shoreline advances over the beach profile on an incoming tide (flooding tide), or recedes on an ebbing tide.

In the UK we mostly experience a semi-diurnal tide which means we experience two high tides and two low tides each day. These occur approximately every 12 hours and 25 minutes. Tidal range (the difference between the low and high water mark) has an important cycle approximately every two weeks, known as the spring-neap cycle. Spring tides have the largest tidal range, often exposing low water sand bars and leading to a faster incoming tide. At some beaches being aware of tide times and height is very important to avoid the risk of being stranded by the incoming tide.

2. Understanding the tide times

Tide times are available for the next 5 days for around 500 locations. The data is provided by the National Oceanographic Centre.

The figures shown indicate the high water and low water times and heights (in metres). The data provided is for the nearest port, which means that whilst these values aren’t completely local to the beach (so you may still prefer to use local tide tables, particularly at locations with double high waters) the tide information should give a good reference for the state of the tide when compared to the forecast times.