Swimming outdoors can be an exhilarating experience, but also unpredictable for many because of the impact of the wind.
Understanding how wind speed affects water conditions, particularly in the ocean, can greatly help you make better swimming decisions and have a more enjoyable swimming experience outdoors.
Both the wind direction and wind speed affect the water. When combined with a swell, strong offshore winds create clean waves, while a strong onshore wind creates a messy white water chop. Cross-shore winds can also affect water conditions and create chop.
I am not a big fan of the wind when swimming outdoors, as it can turn glassy waves into messy white water very quickly.
In this article, I will cover:
- How does wind speed impact outdoor swimming?
- What wind speed is safe for sea swimming?
- What wind direction is best for swimming?
- Does wind speed impact lake & river swimming?
How Does Wind Speed Impact Outdoor Swimming?
It is really important to understand how wind speeds influence the water, as it will have a direct impact on your swim.
Personally, I hate the wind while in the water. Being light, I feel I am at the mercy of wind and tides and pushed in the direction the wind wants me to go and not the direction I want to swim in. This induces a feeling of frustration and, in some instances, mild panic.
Understanding the wind and how it shapes the water has given me renewed confidence, as I can work out when it is just too windy for my capabilities or when the wind is working in my favour, which can result in a great swim.
Wind speed and direction impact water conditions in the following ways:
- The direction of the wind will influence waves and white water chop intensity at sea.
- Wind creates surface chop on lakes and rivers.
- Wind will offer resistance if you are swimming into the wind, which will slow your swim down.
- Wind can blow you off course, as wind and tides interact.
The National Weather Service has produced excellent downloadable PDF charts as a quick reference guide for estimating wind speed and estimating wind speed and sea state. [source]
I have combined this data into one table below, correlating the information, so as swimmers we can estimate the wind speed on land and then estimate what the sea conditions will be.
I have stopped the table at Beaufort 8, which is a gale, but it continues to Beaufort 12, which is a hurricane. You can read more detailed sea conditions on the National Weather Service website.
| Beaufort Scale | Wind | Wind Speed (Knots) | Wind Visual Clues | Wave Height (feet) | Sea Conditions Estimation |
|---|---|---|---|---|---|
| 0 | Calm | 0 | Very calm. Smoke rises vertically. | 0 | Sea like a mirror. |
| 1 | Light Air | 1 – 3 | Little flag movement. Trees still. | < 1/2 | Ripples. No foam crests. |
| 2 | Light Breeze | 4 – 6 | Wind vanes move. Leaves rustle. Wind felt on face. | 1/2 (max 1) | Small wavelets. Crests have a glassy appearance. |
| 3 | Gentle Breeze | 7 – 10 | Flags extended out. Leaves in constant motion. | 2 (max 3) | Large wavelets. Breaking crests. Some white caps. |
| 4 | Moderate Breeze | 11 – 16 | Small branches move. Light debris moved along the ground. | 3 (max 5) | Small waves. White caps. |
| 5 | Fresh Breeze | 17 – 21 | Large branches and small trees sway. Crested wavelets inland on lakes and rivers. | 6 (max 8) | Moderately large waves. White caps and a chance of spray. |
| 6 | Strong Breeze | 22 – 27 | Large branches move. Whistling heard. Umbrellas are hard to use. | 9 (max 12) | Large waves. Spray. White foam crests are extensive. |
| 7 | Near Gale | 28 – 33 | Full tree in motion. Hard to walk in. | 13 (max 19) | High seas. White foam, breaking waves blown in streaks along wind direction. |
| 8 | Gale | 34 – 40 | Small branches break. Very difficult to walk in. | 18 (max 25) | High waves. Foam blown. |
Just knowing the wind speed is not enough, however, as we need to know the direction of the wind as well.
The following table summarises how wind direction will influence sea conditions.
| Wind Direction | Wind Description | Water Conditions |
|---|---|---|
| Onshore | The wind is blowing onto the shore, coming in from the sea. Stand on the beach and face the water. If the wind is blowing in your face, then it is onshore wind. | With a sea swell, onshore wind will create lots of white water and choppy water. You could call the water conditions “messy”, as the onshore wind blows behind the waves and, in effect, pushes them over. |
| Offshore | The wind is blowing out to sea. Stand on the beach and face the water. If the wind is blowing you from behind, then it is offshore wind. | This wind direction is the best for swimming, as it will create glassy and clean waves. As the waves move in towards the shore, the offshore wind helps to stabilise the waves, keeping them formed, which will reduce the impact of white water. |
| Cross-shore | The wind is blowing parallel to the shore. | Cross shore winds can be very tricky as they can create calm water conditions near the shore depending on the swell. However, currents will turn earlier than expected because of the force of the wind. |
What Wind Speed Is Safe For Sea Swimming?
There is not a specified wind speed that is safest for sea swimming.
When determining if sea swimming is safe, always consider tide times, water currents, wind direction, weather conditions, and wind speed in conjunction.
Although wind speeds of 11 knots is considered a moderate breeze with small waves and white caps, this can still be dangerous for inexperienced or weaker swimmers. It really depends on the safety of the beach and the capability of the swimmer.
Always check your local weather and tide times to understand what conditions you are facing.
To get the latest tide charts and tide times for both the UK and around the globe, Tide Charts is a great resource for checking the tidal and wind conditions in your local swim spot.
Only swim within your capabilities and always put your safety first.
If in doubt, don’t go out.
What Wind Direction Is Best For Sea Swimming?
As a general rule, an off-shore wind will create calmer waters nearer to the shore, as waves are pushed out to sea or the force of the incoming swell is met by the force of the off-shore wind.
This calmer water can create flat surface conditions or glassy waves, which can be easier to navigate as a swimmer.
Will An Off-Shore Wind Blow Me Out To Sea?
This is a fear of mine.
Learning to swim as an adult, I have had to deal with a lifelong fear of deep water. Being petite, I am also very light in the water and you can generally tell which way the tides and water are moving when I am in the water as I am the first to drift off-course.
The risk of getting blown out to sea is greatest if you are on an inflatable device or a watercraft such as a kayak or a paddleboard.
There have been countless rescues across the UK and Ireland, just this year alone, where paddle boarders, kayakers and children on inflatable toys have been blown out so sea. [source]
When sitting on top of the water in a light craft or inflatable, you are at the mercy of the wind and tides, so take great care with an off-shore wind if you are kayaking or paddle boarding as the wind can blow you out to sea.
If the wind is strong enough, combined with currents, you can easily drift for miles if you do not have the stamina or strength to return to the shore.
Does Wind Speed Impact Lake & River Swimming?
Wind speed can also impact lake and river swimming. Strong winds will create small waves and surface chop on both lakes and rivers.
In addition, swimming against the wind will slow you down as you face resistance.
Final Thoughts
Wind direction and speed can affect swimming conditions, whether you are swimming in the sea or a lake or river.
The wind speed and direction will affect how waves form and how choppy the water surface is. Generally, an off-shore wind will create flatter surface water conditions which are easier for swimmers to navigate.
On-shore winds or cross-shore winds will create white water caps and chop, which is far more difficult for swimmers to swim through.
Always be aware of your surroundings and swim within your capabilities to ensure a safe and enjoyable swim.
Happy swimming!