Is it safe to climb Corn Du today and tomorrow?

Today on Corn Du is rated Marginal and tomorrow Marginal, from the summit forecast. Summit forecast updated 19:11, 18 Oct. The reasons are below, followed by what the rating can't tell you.

Is it safe to climb Corn Du today?

Marginal Today Sunday 18 October

• Wind and gusts: Summit wind up to 28 mph, gusting 35 mph. That is past the Marginal line (wind 25 mph or gusts 45 mph): expect to be pushed about on ridges and the summit.
• Rain: 0% chance of rain, about 0.1 mm in all.
• Cloud: Cloud cover averages 71% and humidity 82% at summit height. The forecast gives no cloud base height; the main peak page estimates one from the valley forecast.
• Temperature and wind chill: Up to 6°C at the summit, down to 2°C, feeling as cold as -2°C in the wind.
• Daylight: Sunrise 07:43, sunset 18:14: 10h 30m of daylight. The longest route listed here takes about 2h 0m there and back by Naismith's rule, before stops.

Is it safe to climb Corn Du tomorrow?

Marginal Tomorrow Monday 19 October

• Wind and gusts: Summit wind up to 27 mph, gusting 33 mph. That is past the Marginal line (wind 25 mph or gusts 45 mph): expect to be pushed about on ridges and the summit.
• Rain: 100% chance of rain, about 6.2 mm in all. A 60% chance or more makes the day Marginal on its own: wet rock is slippery and wet kit chills you faster.
• Cloud: Cloud cover averages 63% and humidity 89% at summit height. The forecast gives no cloud base height; the main peak page estimates one from the valley forecast.
• Temperature and wind chill: Up to 7°C at the summit, down to 2°C, feeling as cold as -1°C in the wind.
• Daylight: Sunrise 07:45, sunset 18:12: 10h 27m of daylight. The longest route listed here takes about 2h 0m there and back by Naismith's rule, before stops.

What the verdict covers, and what it doesn't

Peakify rates each day Good, Marginal or Poor from the forecast summit wind, gusts, chance of rain and wind chill. Wind of 40 mph or gusts of 65 mph make it Poor; wind of 25 mph, gusts of 45 mph, a 60% chance of rain or a feels-like temperature of -8°C or below make it Marginal. That is all it measures: the weather forecast at the summit.

It does not know your fitness or experience, whether you can navigate in cloud with a map and compass, or what you are carrying. It does not see the state of the path, river levels, snow and ice already on the ground, or how the forecast is changing during the day. A Good day can still go wrong if you start late, turn an ankle or lose the path in mist, and a Marginal day can be fine for an experienced party on the easiest route.

On any day, carry waterproofs, warm layers, a hat and gloves, food, water, a head torch and a charged phone, and know how you would navigate if the top is in cloud. Tell someone your route and when you expect to be down. In winter conditions you need an ice axe and crampons and the skill to use them, or a guide.

Route notes for Corn Du

Pont ar Daf

From Pont ar Daf car park. A wide, pitched path climbs at an even gradient to the col below Corn Du, then a short steep section to the summit. Graded Moderate: a hill path, rough or rocky in places, below the Hard and Scramble grades. In cloud, take care to stay on the path. About 1h 50m there and back by Naismith's rule (2.7 km one way, 431 m of ascent).

Storey Arms via the Tommy Jones obelisk

From Storey Arms. A path climbs past the obelisk and onto the ridge to the summit. Graded Moderate: a hill path, rough or rocky in places, below the Hard and Scramble grades. In cloud, take care to stay on the path. About 2h 0m there and back by Naismith's rule (3.0 km one way, 477 m of ascent).

Full distances, ascent and times are on the Corn Du routes page.

In an emergency

Call 999, ask for the police and then mountain rescue. Mountain rescue teams in the UK are volunteers called out through the police. Give your location (a grid reference from a map or phone app if you can), what has happened, how many are in your group and your phone number, then keep the phone free. If you have no signal, try to move to higher ground or text 999; you need to have registered your phone with the emergencySMS service before for a text to work.

Questions about Corn Du

Is it safe to climb Corn Du today?

Today, Sunday 18 October: mostly dry, up to 6°C at the summit, feeling as cold as -2°C, summit wind 28 mph gusting 35 mph, 0% chance of rain. Rated Marginal. The rating covers the summit weather only; your route, kit and experience matter as much.

Is it safe to climb Corn Du tomorrow?

Tomorrow, Monday 19 October: slight rain, up to 7°C at the summit, feeling as cold as -1°C, summit wind 27 mph gusting 33 mph, 100% chance of rain. Rated Marginal.

How does Peakify decide whether Corn Du is safe to climb?

Peakify rates each day Good, Marginal or Poor from the forecast summit wind, gusts, chance of rain and wind chill. Wind of 40 mph or gusts of 65 mph make it Poor; wind of 25 mph, gusts of 45 mph, a 60% chance of rain or a feels-like temperature of -8°C or below make it Marginal. It does not judge your fitness, kit, navigation or the state of the path.

Who do I call in an emergency on Corn Du?

Call 999, ask for the police and then mountain rescue. Give your location (a grid reference if you can), what happened and how many are in your group. Stay with the casualty and keep them warm.