Whether you're heading out for a surf, a swim, or simply exploring the shoreline, understanding a beach forecast can help you stay safe and make the most of your time by the sea.
From wind strength to tide times and wave height, these forecasts are packed with useful details — if you know what to look for. Here’s how to read and interpret the key elements of a beach forecast, and why they matter before you get in the water.
What is a beach forecast?
Beach forecasts provide information about weather conditions at the coast, which is particularly useful for those planning on entering the water. Surfers, swimmers and anyone doing water sports will find these particularly helpful in deciding which beaches to use at different times and in different conditions.
A beach forecast will take into account a number of different elements: tide times, wind direction, and height, period and direction of waves. We’ll explain what each one does here – and why you might find them useful.
Always look out for the RNLI beach flags before entering the water and seek advice from local lifeguards if you have any concerns. Stay safe in the sea! Remember – rip currents aren't referenced on beach forecasts, so you'll need to stay vigilant.
What is wind direction?
On a beach forecast, wind direction is shown with an arrow. This will show the compass direction of the wind (up is north, down is south). If the arrow points from sea to land, the wind will be blowing in that direction. This is known as ‘onshore’, while the reverse is referred to as ‘offshore’. If the arrow is pointing somewhere between the two, the wind will be blowing across the beach – ‘cross-shore’.
The number shown is the average wind speed, either displayed in kmph or mph.
Offshore winds are risky for those using inflatables, paddleboards or sea kayaks, because those winds can drag you out to sea. Strong onshore or cross-shore winds, meanwhile, might mean the waves will be rough. Cross-shore winds are tricky for most water sports other than kitesurfing or windsurfing.
Surfing is best suited to offshore winds, because they create cleaner, more powerful waves that are better for longer rides and better manoeuvres.
Remember, wind direction and strength can change over the course of a day, so keep an eye on conditions and check the forecast again if you’re not sure.
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Height of waves
The offshore wave forecast information tells you what the wave conditions are like in open waters a couple of miles from the beach. Individual waves can obviously vary in height, so a standard measure known as “significant wave height” is used for this measurement – i.e. the average height of the highest third of all waves.
What is wave period?
The “period” is the average number of seconds between the crest of one wave and the crest of the next, 1-2 miles out to sea. Again, an average standard measurement is used, known as the “peak period”, which is the time between the most powerful waves. The closer the waves are together, the messier the conditions might be and the shorter runs you might get on a surfboard. Surfers generally prefer longer wave periods, typically 10 seconds and above, as these are usually more powerful and organised waves.
Tide times on beach forecasts
One of the main aspects of a beach forecast is the tide times. This will tell you when low and high tide will be on that day, which will determine how much beach is available – and whether you have a risk of being stranded by a rising tide.
Surf forecast components
While they may not always be included in a beach forecast, swell and surf height will always be included on surf forecasts. You might also see an indicator of the temperature both in and out of the water – and, on some apps, a suggestion of wetsuit thickness to go for at your British surfing beach of choice.
What is swell?
Swell refers to the energy of waves travelling across the ocean, usually generated by distant storms. Swells are generally bigger in winter, therefore, as there are more powerful storms and longer, stronger winds out to sea. Swell is the source of the waves that surfers ride, so is really important to understand in conjunction with wind.
Groundswell and windswell are two types of ocean wave. Groundswell is what we generally talk about when we talk about swell (or see it on a surf forecast), because it often has longer wave periods as it originates from distant storms. These longer wave periods are useful for surfers. Windswell, meanwhile, is generated by winds closer to the shore and often has shorter wave periods.
What is surf height?
Surf height is a measure used on surf forecasting calculated by the wave direction, the wave period and the beach slope. While wave height refers to the size of waves out at sea, surf height refers to the size of waves as they are breaking at a surf spot – so is often more of an accurate reflection of the surf conditions.
Best beach forecast apps
Windy.app is a good app for those particularly interested in wind and wave data, while Surfline specialises in surf conditions. Surfline also has surf reports, condition ratings and live surf cams, so surfers are able to have a look at current wave conditions without having to go to the beach themselves to check. The Met Office weather app also has wind forecast, tide times and beach safety advice on its beach forecasts.
Top image: Two RNLI lifeguards in uniform watching Bournemouth beach from the pier during summer (credit: Getty Images)
