Why coastal weather refuses to behave

Walkers who are perfectly confident in the hills often come unstuck on the coast. A coastal path is a narrow, exposed place where sea, land and wind all shape the forecast at once. Conditions can turn inside twenty minutes: a bright morning on the headland can end in thick sea fog with a forty-knot gust coming over the top. The forecast for the nearest inland town is usually poor guidance. Read an inshore waters forecast alongside a hill or mountain forecast, and when the two disagree, plan for the worse of them.

Two local effects matter most. Wind accelerates over headlands and through gaps, so a sheltered car park can be calm while the cliff top is a battle. And a sea breeze can arrive on an otherwise still day, dragging cloud and damp air inland and turning a warm afternoon cold and clammy within the hour. The same is true along the Norwegian coast and the Bohuslän skerries, where weather comes in off the water faster than the models expect.

Tides: the one thing you should never guess

On many coastal routes the tide is not background information, it is the route itself. Beaches, tidal causeways, low-tide crossing points and the flat rock platforms below the cliffs all disappear under water, and the sea does not return at a steady rate. The rule of twelfths is worth knowing: over roughly six hours the water moves one twelfth of its range in the first hour, two in the second, three in the third, then three, two and one. The middle hours are when the sea advances fastest, and they are exactly when tired walkers are still dawdling along a wet beach.

• Get times from a local harbour tide table rather than the nearest town, and check whether the range is spring or neap. On a flat beach the difference can push the waterline fifty metres further up the sand.
• Allow for the weather. Sustained onshore wind and low pressure can add considerably to a high tide, sometimes more than the forecast suggests.
• Never wade a rising tide to save a detour. Turn back, climb out or wait it out somewhere dry and safe.
• In Scandinavia, Baltic coasts have almost no tide, but wind-driven water levels can shift a metre or more in a single day. On the Skagerrak and North Sea sides, normal tides apply.

Cliff edges, erosion and ground that will not hold

Coastal erosion is constant, and the edge is often further back than the map or your memory suggests. Boulder clay, glacial till and soft sandstone crumble quietly from below, leaving an overhang of grass that looks solid and is not. Keep well back, especially after rain, and never trust a fence to mark the current edge — many follow a line drawn decades ago.

• Give yourself a body length plus from any unguarded edge, more in wind or wet conditions.
• Watch for fissures running parallel to the cliff line, and for cracks radiating back from the top.
• Treat gullies and narrow inlets with suspicion. They are usually wet, loose and awkward to escape from.
• Wet grass on sloping rock is the single most common cause of a slip on coastal ground.

When visibility collapses

Sea fog and haar can arrive in minutes and reduce visibility to a few dozen metres. Stop, put on a layer, eat something, and take a moment. Then navigate in short, deliberate legs: take a compass bearing to a feature thirty or forty metres away, walk to it, confirm your position, take the next bearing. Use handrails where you can — a wall, a stream, a fence line — and keep the map and compass out even if you also have a device. Contour across a slope rather than descending blindly, because descending in fog on the coast usually leads towards steep ground, not away from it. If you cannot confirm where you are, retrace your steps. The path will still be there next week.

Wind, cold and staying on your feet

Coastal wind carries moisture and salt, and it chills far faster than a dry inland wind of the same speed. Windproof and waterproof layers, a hat, gloves and a spare warm layer belong in your pack all year, not just in winter. Spray makes rock greasy; add wet boots and a gust and a straightforward path becomes a serious proposition. If you find yourself crouching to stay steady, that is your cue to turn inland or drop to lower, sheltered ground.

Planning for the worst: being found quickly

Tell someone your route, your expected finish time and what you are wearing, then message them when you are back. Carry a whistle, a headtorch and a spare battery, and keep your phone in a waterproof case, warm and out of the wind — cold batteries die quickly. Signal is patchy in the best coastal valleys, so send a location update whenever you have bars.

If something goes wrong, dial 999 and ask for the coastguard in the UK. In Norway, 120 reaches the coastal radio for emergencies at sea, while 112 covers Sweden and Denmark for all emergencies, including mountain and coastal rescue. Be ready to give a grid reference or coordinates, a description of the ground and the condition of anyone injured. Ten minutes spent on that plan at home is the cheapest safety kit you will ever carry.