The AJ Bell Great South Run is one of the UK’s most iconic running events, drawing thousands of participants and spectators to Portsmouth’s historic seafront each October.
As runners prepare to take on the 10-mile challenge, the weather will play a crucial role in shaping the day’s experience. Here’s a detailed look at the forecast and practical advice to help you make the most of this year’s event.
The forecast: What to expect on race day
Sunday is set to begin on a damp note, with rain lingering as the day gets underway. However, as the morning progresses, the rain is expected to clear eastwards, gradually giving way to some brighter spells. Winds will slowly ease, making for more comfortable running conditions as the day unfolds. While the early part of the race may feel a little wet underfoot, the improving weather should lift spirits for both runners and supporters alike.
Looking ahead to Monday and Tuesday, the forecast indicates a mix of sunshine and blustery showers, but for race day itself, the main message is to be prepared for a damp start, followed by a gradual improvement as the skies brighten and winds subside.
The route: Portsmouth’s landmarks and coastal scenery
The Great South Run offers a unique tour of Portsmouth’s most famous sights. The race starts on Clarence Esplanade, taking runners past the Spinnaker Tower and through the Portsmouth Historic Dockyard, before finishing at the historic Southsea Castle. The flat, fast course is renowned for its scenic views of the Solent and the city’s maritime heritage, making it a favourite among both elite athletes and fun runners.
🌤️ Saturday vs Sunday 🌧️
— Met Office (@metoffice) October 17, 2025
Making plans for the weekend?
Saturday is looking mostly dry - a great day to get outside
Sunday will be wetter... perfect for puddle jumping! 💦 pic.twitter.com/dhi4FCaG2C
Since its inception in 1990, the event has seen hundreds of thousands of runners cross the finish line, raising millions for charity and creating unforgettable memories along the stunning south coast. This year marks the 35th anniversary of the Great South Run, promising another day of celebration, achievement, and community spirit.
Race day advice: Preparing for the weather
- Dress for the conditions
With a damp start expected, it’s important to dress appropriately. Consider wearing an extra layer or an old top to keep warm at the start line.
- Footwear and comfort
Ideally, you should have trained in your running shoes for at least a month before the event to ensure comfort and avoid blisters. Wet conditions can increase the risk of chafing, so apply Vaseline or a similar barrier to areas prone to rubbing, such as the groin, upper thighs, underarms, around bra bands, or between toes.
- Pacing and crowd management
The first few miles of the Great South Run can be crowded, particularly for those starting further back in the field. Don’t waste energy weaving in and out of other runners; instead, maintain a steady, even pace and focus on enjoying the atmosphere. The field will naturally thin out as the race progresses.
READ MORE: 'Brutal' cold snap? 'Barrage of snow'? Met Office weather headline review
- After the finish
Once you cross the finish line at Southsea Castle, collect your bag as soon as possible and put on warm, dry clothing to avoid getting cold. Take a drink as soon as you can to begin rehydrating after your effort. The combination of a damp start and easing winds means it’s especially important to avoid lingering in wet kit.
While the weather may present a few early challenges, the forecast for Sunday suggests that conditions will improve as the day goes on. By planning ahead and dressing appropriately, you can ensure a comfortable and enjoyable experience from start to finish. Remember to look after yourself and your fellow runners, and take pride in being part of one of the UK’s most celebrated running events.
Keep up to date with weather warnings, and you can find the latest forecast on our website, on YouTube, by following us on X and Facebook, as well as on our mobile app which is available for iPhone from the App store and for Android from the Google Play store.