Changeable by nature
Cornwall’s weather is shaped by its position on the edge of the Atlantic. Systems arrive from the west, and with little land to slow them, they can come quickly. A morning of sunshine may be followed by squally showers, and the reverse is equally possible. Forecasts are useful but cannot capture every local shift, particularly where hills, valleys and coastline create their own microclimates.
The overall character of the climate is gentle, as explained in the article on the mild climate. But a mild average can hide sharp short-term changes, which matter most to anyone walking on open ground.
Moorland weather
Higher ground is exposed. The moors have few trees or buildings to break the wind, and they sit above the surrounding lowland, so they are usually windier, cooler and wetter than the coast or valleys a few miles away. The details of moorland weather are worth understanding before heading out.
- Cloud and hill fog. Moist air forced upward over the hills cools, and cloud can form around the tops while the lowlands remain clear. A hill can disappear into mist within minutes. Visibility may drop to a few yards.
- Rain. Showers can be heavy, and in prolonged wet weather streams rise and boggy ground gets worse.
- Wind. Exposed summits and ridges can be much blustier than sheltered paths below. Wind chill makes it feel colder than the temperature shows.
- Temperature. Even in summer, a wet, windy day on the high moor can feel cold, particularly if you are damp.
Because the moors are open, people can lose their bearings in fog. Many paths are faint, and the landscape looks similar in all directions. Old mine workings, boggy hollows and rock outcrops are further hazards on poor-visibility days, so the sensible choice is often to stay low or turn around.
Coastal weather
The coast has its own pattern. Cliff tops catch the full force of Atlantic wind, and gusts can be strong enough to unsettle a walker near an edge. Sea spray can reach surprisingly far inland in rough conditions. In some weather, the north coast, facing the open Atlantic, is more exposed than the south coast, though both can be harsh. The two coastlines and how they differ are discussed in the article on north and south coast.
- Sea fog. When warm, moist air passes over cooler water, a bank of low cloud or fog can roll onto the shore, sometimes called sea fret or sea mist. It can be thick on the coast path while the sun shines a mile inland. Cliff paths become especially risky when you cannot see the edge.
- Swell and surf. Distant storms can send large waves to the coast even on a calm, sunny day. Rip currents and heavy surf are explained in the article on rip currents.
- Tides and weather together. Strong onshore winds combined with high tides can raise water levels and bring waves higher up beaches and sea walls than usual.
Reading the signs
Weather forecasts are the starting point, but a few local signs can help:
- Clouds thickening and lowering, especially from the west, often precede rain.
- A sudden rise in wind or a change in wind direction can signal an approaching front.
- Distant headlands that look unusually sharp can mean moist air, though such folk signs are not reliable by themselves.
None of these replaces a current official forecast. Check the forecast for the specific area and altitude, and look again before setting off, since conditions may differ from the night before.
Preparing for a walk
A few habits make most walks safer and more comfortable.
- Dress in layers. Pack a waterproof jacket and, if possible, waterproof trousers, a warm layer and a hat. Cotton gets cold when wet; synthetic or wool fabrics are usually better.
- Wear proper footwear. Boots or shoes with grip are best on wet rock, mud and grass.
- Carry a map and compass, and know how to use them. Phone signal is patchy on moors and in coves, and batteries run down in cold and wet.
- Tell someone your route and when you expect to return.
- Bring food and water, plus a torch in case you are out late, because dusk can fall quickly in overcast weather.
- Be willing to turn back. Deteriorating weather is a better reason to change plans than a tight schedule.
For the coast, also read the guidance on coast path walking and check the tide tables if your route crosses beaches or passes below cliffs.
If the weather turns
If fog descends on the moor, stop and check your position before moving. Follow a known path or a handrail feature such as a wall or stream if you are certain of it. Avoid cutting across country. If you are lost or injured, call the emergency number and ask for the police and mountain rescue on the moor, or the coastguard on the coast, and give your best location. On the cliffs, move back from the edge in strong wind and do not take photographs near drops. If lightning is forecast, stay off exposed tops and rocky outcrops, and avoid shelter under isolated trees.
Seasons in brief
Spring and autumn often bring fast-changing conditions. Summer has the longest daylight and generally the best chance of settled weather, but fog and showers still occur. Winter days are short, wetter and windier, and cold snaps can leave paths icy at higher elevations. Nothing here is a guarantee, and local forecasts should always take priority. With some preparation and flexibility, though, changeable weather becomes a feature of the landscape rather than a threat to a good day out.