Three Forts Marathon

Three Forts Marathon 2025 Course Analysis

Three Forts Marathon is a full marathon held in Worthing, United Kingdom, scheduled for Sunday 4 May 2025. The course is run on trail surface with 1949m of total elevation gain, reaching a maximum altitude of 235m above sea level. For registration and full race details, visit the official Three Forts Marathon website.

Elevation Profile

This is a very challenging course with 1949m of total elevation gain — significantly more than the average trail marathon. The route ranges from 2m to 235m above sea level (233m range). Hill training is essential, and runners should expect a significantly slower time compared to a flat course.

Expected Race Day Weather

Based on historical weather data for May, the expected race day conditions are as follows. Near-ideal running temperatures are expected, ranging from 7°C to 14°C. This temperature range is widely considered optimal for marathon performance, allowing efficient heat dissipation without cold-related issues. There is a low chance of rain (0%), so dry conditions are likely.

Surface Type: Trail

Three Forts Marathon is a trail race, meaning the course includes unpaved surfaces such as dirt, gravel, or forest paths. Trail surfaces are inherently slower than road courses due to uneven footing, technical sections, and often steeper gradients. Trail-specific shoes with good grip are recommended, and runners should expect a finish time 10-20% slower than their equivalent road marathon time.

How Difficult Is Three Forts Marathon?

Our difficulty rating for Three Forts Marathon is calculated using a model that combines elevation gain, temperature impact, and surface type. Use the difficulty calculator above to enter your target finish time and see exactly how many minutes this course would add or subtract compared to a perfectly flat, cool, road-based marathon. Faster runners and slower runners are affected differently by the same course conditions, so the difficulty is personalised to your pace.

Looking for an easier marathon or a tougher challenge? You can also compare Three Forts Marathon against other marathons to find the right race for your goals.