When planning an open water swim on the wild west coast of Argyll in Scotland, there are a number of things to consider. I usually check the wind direction and speeds, swell height and tides in advance. I’ve been using windy.app for a while now and it’s a very useful aid in all of these regards.
Firstly, I love how visual it is. I can zoom into my area and get an instant visual of the wind speed, gusts and direction according to the landscape and water of my local context. It also gives me an idea of the swell, tides and their range in a given location. Below I’ll share more about why checking this kind of data is useful and how the windy.app assists with this to provide an accurate prediction for my swims.
Wind direction and speeds/gusts
This information is quite important as by observing the arrows on the app it can provide a prediction of whether the winds will be offshore on onshore. Ideally and depending on the wind strength I’m hoping for an offshore wind direction ie blowing from land out to sea. This is because as the waves are coming into shore, a wind direction originating from land will flatten those waves close to shore, making it suitable for a decent swim. It’s also worth checking wind gusts too, which windy.app provides data on. The wind gusts refer to the temporary increases in wind speed that are predicted to occur and worth being aware of.
Winds not only impact on the quality or the efficiency of the swim but also have an impact on how cold you‘ll feel, in other words the wind chill. The wind chill is the impact that a wind speed or gust can have on the temperature it feels like. The air temperature forecast on its own doesn’t take into account how cold it will feel with wind chill factored in. A good approximation of the wind-chill temperature can be found by multiplying the wind speed by 0.7 and then subtracting that value from the air temperature. A strong wind from any direction can make it feel a lot colder and therefore impact on the projected risks of hypothermia and cold incapacitation in and out of the water.
The windy.app can also indicate accurate predictions of local swell height. What we mean by “swell” is the regular, longer period waves generated from some distance away. This will certainly come in handy when planning for my adventure swimming tours in the summer with Fyne Sea Tours, as we’ll be venturing further from shore into open water. It’s also relevant if I’m swimming close to shore. Anything in excess of about 1.5 metres swell height makes progressive swimming difficult.
Tides & Tidal Range
Last but by no means least I’ll check the tides and tidal range of my swimming location. Windy.app provides a bit more detailed information than most other sources in terms of this data so It’s worth paying for the PRO version. As I’ve mentioned it’s a very visual app which benefits me as I’m a visual learner! I like that on the app I can see a visual graph representation of the passage of the tides from low to high, including accurate approximations of the range. Tidal range refers to the difference in depth between high and low tide or a flood and ebb tide. I’ll use the tidal range data especially when exploring a new swimming location.
Given the corrugated landscape of the Argyll coastline and isles it means we have several sheltered sea lochs and bays which offer a low tidal range. This means there is minimal difference between high and low tides. This difference can be as low as around 1 metre. The low movement and stability of the current and swell means I can often safely swim at different points in the tidal cycle.
However, in certain locations the tidal range is larger, 2 metres+. This means more water is moving inbetween slack water at high tide and the ebbing water at low tide which can generate stronger currents. In this situation I’d need to time my swim more carefully.
You’ll notice that throughout this article I’ve used terms like “approximation”, “indication” and “prediction” when referring to what the windy.app offers. The windy.app is an aide which supplements my knowledge of a particular location. When planning a swim I draw on local knowledge and lived experience in the first instance. This comes from my own experience of the environment as an open water swimmer and the knowledge I’ve gained to date from local sailors, fishermen, coast guards and other water sport professionals who I’ve sought out.
I always say that if you’re visiting a new area on holiday and want to explore the open water seek out experienced professional open water coaches and guides who know the water and landscape. We can give you a safe and enriching experience. It’s what I do when I visit other areas such as booking on with Immerse Hebrides when I visited the Isle of Lewis in the summer for an adventure swim.
The windy.app is fantastic in that it supplements my planning process for a swim. There are other apps who offer similar information but in my opinion the PRO version on Windy.app offers the most detailed and comprehensive data to help me predict what conditions will be like. Give it a go!