Corn Du is a 872m (2859ft) Wales hill classified as a Nuttall, one of 442 Nuttalls in Wales. Check today's Corn Du summit weather including wind speed, temperature, rain risk and cloud cover before heading out. Weather on the Welsh hills can change quickly at this altitude.
Corn Du is a summit of the twin topped Pen y Fan and the second highest peak in South Wales at 871. 5 m (2,864 ft), situated in the Brecon Beacons National Park.
Geology: The bedrock here is Brownstones Formation — Interbedded sandstone and argillaceous rocks — a sedimentary rock formed from compressed sand grains. Age: Lochkovian Age.
Planning to walk Corn Du? Our summit weather forecast shows live conditions at 872m including wind speed, wind chill, temperature, freezing level, cloud base and rain risk. The forecast updates hourly using data from 7 weather models blended into the HILLANDGLEN ensemble — accuracy-weighted so the best-performing models have the most influence.
Key conditions to check before climbing Corn Du: wind chill (the real temperature you'll feel on exposed ridges), freezing level (whether ice and snow are likely on the summit), cloud base (whether you'll have visibility at 872m), and wind gusts (which can be significantly stronger on exposed summits than in the valley below).
Corn Du weather can change quickly at 872m. Valley conditions often differ from the summit — our forecast applies lapse rate adjustments to give you the actual temperature and wind at the top, not the nearest town. Check the 14-day outlook to find the best day to walk Corn Du.
Frequently Asked Questions
How high is Corn Du?
Corn Du is 872 metres (2859 feet) above sea level. It is classified as a Nuttall in Wales.
What is the weather like on Corn Du?
At 872m, conditions on Corn Du are noticeably different from the valley floor. Expect temperatures 4-6°C colder at the summit, stronger winds on exposed sections, and cloud that can sit on the tops. Check the live summit forecast on hillandglen.com for wind chill, rain risk and visibility before your walk.
Is Corn Du a difficult walk?
Corn Du at 872m is a hill walk requiring reasonable fitness. The main challenges are weather-related: wind, rain and poor visibility can make navigation harder. Check the summit forecast before setting out and carry waterproofs, warm layers and a map.
What is a Nuttall?
A Nuttall is a mountain in England or Wales over 2,000 feet (609.6 metres) with a drop of at least 15 metres. Compiled by John and Anne Nuttall, the list contains 442 peaks and is more inclusive than the Hewitts due to the lower prominence requirement.
When is the best time to climb Corn Du?
The best months for climbing Corn Du are typically May to September, when days are longest and weather is generally drier. Summer offers the most stable conditions and longest daylight hours. Autumn can also be excellent with clearer skies and golden light.
Free summit weather forecasts for over 20,000 British and Irish hills. Designed for hikers, runners, and climbers who need accurate mountain conditions — not just city weather.
