Race day on this page is Oct 18, 2026.
10 MilesForecasts live
Great South Run
Sunday, October 18, 2026Portsmouth, Hampshire, UK
Goal time
1:35:00
Adjusted time (preview)
About 12 m of climbing and 12 m of descent. Mostly flat.
Almost all within 2%No grades over 6%No counted climbs
Impacts
Based on the forecast, 3 days out.
Elevation
Heat
Wind
Total Impact
Race Pass: personalised finish time, adjusted splits, and your race-day pacing plan.
Race Day Forecast
The live outlook for this start.
11°C
Feels like 11°C
Race start: 10°C → 12°C
Forecast: clear, with strong winds
Race Day Pacing
Personalized pacing with weather-adjusted strategy tailored to your fitness level.
Race Pass turns this into your personalised split plan, paced for this course and forecast
Live forecast, route, and elevation
Cloud Cover
8%
Wind
23.5km/h
Humidity
67%
WBGT
9.4°C
Race Day Pacing
Personalized pacing with weather-adjusted strategy tailored to your fitness level.
Race Pass turns this into your personalised split plan, paced for this course and forecast
Live forecast, route, and elevation
Race Timeline
Race starts 10:35
10:00
Starts 10:35
10°C
Feels 10°C
0.0 mm
4%
22.0 km/h
gust 43.8
11:00
4.2 km
11°C
Feels 11°C
0.0 mm
4%
23.8 km/h
gust 47.9
12:00
14.4 km
12°C
Feels 12°C
0.0 mm
4%
23.9 km/h
gust 49.7
13:00
Finished
13°C
Feels 13°C
0.0 mm
6%
23.4 km/h
gust 49.3
Conditions over time
18 Oct 2026 · Hover or drag to explore
67% humidityDew 5.5°CWBGT 9.4°C0.0 mm (4%)
11°CFeels 11°C
10:35-12:10
TempDewWBGTRain
23.5 km/h
gust 47.7 km/h
WindGust
Historical weather
2 held editions. Race mornings only, not nearby dates. This is not a forecast.
13°C
11 - 16°C range
Overcast on average
Historical: overcast, with strong winds
Historical average
2 held editions. Race mornings only, not nearby dates.
2023-2025
Cloud Cover
79%
0 - 100% range
Wind
20km/h
1 - 34 km/h range • prevailing SE
Humidity
84%
65 - 93% range
WBGT
11.9°C
11.1 - 11.9°C range
Race morning history
Last 10 years, around the 10:35 start hour. Typical mid-October air averages 13°C (about 10°C to 16°C in that window). The bands are that history, not a forecast range. Hover or drag to explore.
Race-morning temperature
Most mornings
12-15°C
Almost all
11-16°C
Humidity
84%
Dew
11°C
WBGT
11°C
13°CAverage
10:35-11:46
Almost all (90%)Most mornings (70%)AverageRain
Year pills: green is favorable heat. Amber is moderate. Red is challenging.
Blue is most mornings. Dashed lines are the rare tails. Pink is the average. The bands are historical race mornings, not a forecast range. Blue columns are rain on the right scale. This assumes a 1:11. You can set your own time in the app.
Typical race-morning wind
Where the wind usually came from on race morning, not where it was going.
ENE
Most frequent (15%)
Wind speed
0-6 km/h
6-13 km/h
13-21 km/h
21+ km/h
Year pills: green is favorable wind. Amber is moderate. Red is challenging. Colours assume no drafting.
A start that feels cool is not a promise about the second half.
Related races
Same city, region or country, when we can resolve them. World majors also point to each other.
View race map for this area.
Make sense of the conditions
- Dew point, WBGT and running in the heat
Read the heat and humidity before deciding what pace makes sense.
- When drafting helps your running pace
A group can help, but its pace and the conditions still need to suit you.
- Pacing the climbs and descents
Use the course profile to think about effort, not just splits.
Pacing and conditions FAQ
Beyond conditions
Conditions are only part of the race-day loss
Pacing mistakes often add several minutes, sometimes more than conditions alone, especially when the course and conditions are not ideal.
What your plan includes
Everything you need to turn this race preview into a usable race-day plan.
Personalized pacing
Effort and pace guidance tuned to this course profile.
Weather-adjusted splits
Split targets that account for heat, wind, and elevation.
Heat adaptation & drafting
Adjust for your heat tolerance and drafting preferences.
Get your personalised race plan for Great South Run.
Pacing, splits, and race-day strategy personalised to your fitness and this course.
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