South Downs Way 100 course

Source: The distance and the ascent are from the race organiser. We calculate the descent from the organiser ascent and the elevation difference between the start and the finish. The elevation profile and the gradient data come from a 25 m digital elevation model (EU-DEM). All elevations are to the nearest 10 m (50 ft).

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About the course

The South Downs Way 100 is a c.99 mi160 km point-to-point ultramarathon that follows the South Downs Way National Trail through the South Downs National Park in southern England. It starts in the historic city of Winchester and heads east along the chalk ridge of the Downs. It passes Queen Elizabeth Country Park, Amberley, Devil's Dyke, Ditchling Beacon and Alfriston before finishing in Eastbourne on the south coast.

Although it rarely rises above c.800 ft240 m, the course has roughly 12,450 ft3,800 m of elevation gain and 12,750 ft3,890 m of loss. This builds up over a steady series of rolling climbs and descents as the trail repeatedly drops to cross river valleys before climbing back onto the ridge.

The course is mostly on trail, largely flinty chalk tracks and grassy downland paths across open, exposed ridgeline.

The South Downs Way 100 course climbs around 12,450 ft3,800 m and descends around 12,750 ft3,890 m over its c.99 mi160 km distance. That makes it the least hilly course currently on TrailVu, with just over half the climbing of the Montane Lakeland 100 over a similar distance. Its gain per km is closest to that of the Leadville 100, although the climbing comes as a steady series of short, rolling ascents rather than long mountain climbs.

Ascent & descent analysis

In mid-June, the South Downs usually offer settled early-summer weather, with daytime temperatures typically around 21°C70°F and overnight temperatures of around 11°C52°F. Some rain is likely, and the exposed chalk ridge is often breezy.

Much of the route has little shade, so warm, sunny days can feel hot on the open downland. Rain can make the chalk and flint tracks slippery underfoot.

The weather data has been obtained using the Open-Meteo historical weather API.

Conditions at the start line

The pictograms below show the conditions at the start of the course on the race date in each of the last five years.

Temperature range on course

Temperatures experienced on course are impacted by elevation. The graph below shows the temperature range for the five most recent events at different parts of the course.

Daylight hours

The graph below shows the daylight hours on the day of the 2027 edition (12 June), in local time.

The South Downs Way 100 starts in Winchester at roughly 350 ft100 m, reaches a high point of only around 800 ft240 m, and finishes at sea level in Eastbourne. Altitude plays no part in the race, so the challenge comes from the distance and repeated rolling climbs rather than thin air.

Below 1,500 m, altitude has a negligible effect on VO2max, so the VO2max decline line is not shown for this course.