Semi-Marathon de Boulogne-Billancourt ·
What will race morning in Boulogne-Billancourt cost you?
Past starts: 8°C typical, 3 to 12°C since 2021.Live forecast opens 31 October.
- ★★★★★5.080+ ratings
- 2,750+runners
- 100countries
On a computer? Scan with your phone camera to get the app.
Works with Apple Health01 · The conditions
Race-day weather
Race-day forecasts appear 15 days before the race. Until then, here is what race morning has looked like.
Explore historical weatherGet Boulogne-Billancourt race-morning weather on your phone when it opens.
Set up Boulogne-Billancourt in the app now: your goal, your start, your pace plan. The race-morning forecast lands in it in race week.
On a computer? Scan with your phone camera to get the app.
02 · Same effort, different day
What the weather may cost your goal
1:40:00 goal. On a typical race morning here, expect about 1:40 to 1:41. Main factor: wind.
- Heat and sun0%
- Wind and comfort0%
- Weather total0%
RunWeather’s pace model, one weather hour at your goal effort: weather at 10:00 local using the five-year race-morning average. A planning preview, not a predicted finish. Hills, turns, shelter, fuelling, heat adaptation and wave timing are not modelled here; rain is left out because a probability is not a measured rain rate. Explore the heat pace calculator.
View even-pace checkpoints
| Distance | Elapsed time |
|---|---|
| 5.0 km | 0:23:42 |
| 10.0 km | 0:47:24 |
| 15.0 km | 1:11:06 |
| 20.0 km | 1:34:48 |
| 21.1 km · Finish | 1:40:00 |
In the app
Your race plan, on race morning
Add the Semi-Marathon de Boulogne-Billancourt and the app keeps your plan current until the gun.
Goal pace against race-day pace
What your goal is worth on this morning’s weather, per km and at the finish.
How to spend it
Start, middle and finish, against your average.
What slows you
Heat, wind and hills, each in minutes.
Reference
Everything else about race morning
Open any row for the full detail.
The course21.1 km · 26 to 54 m
The Semi-Marathon de Boulogne-Billancourt is a half marathon in Boulogne-Billancourt, France. The map is the 2023 course. Check the organiser's map for this year.
THE COURSE21.1 km1×Zoom to drag the route. Keyboard: + / −, arrows, Home to reset.
2023 course. Check the organiser’s map for this year.
ELEVATION26–54 m0.0 km- Elevation
- 39 m
Hover or drag to explore. Use ← → when focused.
The 2023 course from RunWeather's race catalogue. The next edition may differ; elevation is approximate. Elevation along that course, not confirmed for this year. Official race site ↗01The first start is listed at 10:00 local time. Check the forecast for your own wave or corral start.
02Compare the conditions at your start and expected finish before settling on kit and effort.
03Confirm late changes to the route, start wave and logistics with the organiser.
Race-window historyLast 5 years, race date ±5 days
A range for planning Semi-Marathon de Boulogne-Billancourt: weather near Boulogne-Billancourt on race morning, the last 5 years (2021 to 2025, race date ±5 days). Not a forecast.
Typical start-hour air8°C10th–90th percentile 3°C–12°CDew point / humidity7°C93% relative humidityStart-hour wind14 km/hDirection varies by dayHours with rain24%Historical frequency at this hourAIR THROUGH THE RUN8°C → 11°C by +4hThe five-year picture
10:00- Air temperature
- 8°C
- Humidity
- 93%
- Wind
- 14 km/h
- Hours with rain
- 24%
Hover or drag to explore. Use ← → when focused. Shading: middle 80% of sampled temperatures.
Five-year average Middle 80% of sampled hoursThe sampled air warms by about 3°C across four hours. Check your expected finish-hour forecast, not just the start.
WIND CONTEXTWhere the breeze came from
WIND FROMSW16 of 55 samples · 29%
Mean 19 km/hThe petals show how often the wind came from each direction at the sampled start hour. They do not predict the direction on race day.
A city-point wind rose cannot tell you which parts of the course will be sheltered or exposed. Use the live forecast and the organiser’s route map together.
Method: 55 ERA5 hourly samples at 10:00 local time, across 11 calendar days per year in 2021–2025. The sample uses the hour containing the advertised first start; waves may start later. Grid weather is modelled reanalysis, not an on-course station reading. Open-Meteo Historical Weather API . Data generated 2026-10-14.
Semi-Marathon de Boulogne-Billancourt FAQs7 questions
When is the 2026 Semi-Marathon de Boulogne-Billancourt?
Semi-Marathon de Boulogne-Billancourt is listed for 15 November 2026. Confirm the latest details on the official event website before travelling.
Is the weather shown a forecast for the Semi-Marathon de Boulogne-Billancourt?
Only from about 15 days before the race, when the page shows the live race-day forecast. Before that, you see the weather near the city on the mornings around race day in the last 5 years: what is typical, not what will happen. Monthly averages, when shown, cover every hour of the race month.
What is race morning usually like at the Semi-Marathon de Boulogne-Billancourt?
Around the 10:00 start, mornings around race day near Boulogne-Billancourt in the last 5 years averaged 8°C, 93% humidity and 14 km/h wind. Most started between 3 and 12°C. This is weather near the city, not a reading from the race itself or a forecast.
Which recent year had the warmest race morning at the Semi-Marathon de Boulogne-Billancourt?
2023. Around race day that year it was about 10°C around the 10:00 start, against 8°C on an average year.
Which recent year had the windiest race morning at the Semi-Marathon de Boulogne-Billancourt?
2023, with about 20 km/h of wind around the 10:00 start. Over the last 5 years the wind here came mostly from the south-west.
How should I pace the Semi-Marathon de Boulogne-Billancourt on a warm day?
1:40:00 goal. On a typical race morning here, expect about 1:40 to 1:41. Main factor: wind. If race day comes in warmer, start a little easier than goal pace, run by feel to halfway and drink early. Plan my race gives your splits for the day.
Can past years predict the weather on race day at the Semi-Marathon de Boulogne-Billancourt?
No. They show what race morning is usually like, not what this year will bring. Check the live forecast in the last 15 days, look at the hours through your expected finish, and follow the organiser for start and course updates.
Sources and race informationOrganiser, weather data, guide reviewed 2026-10-13
Past race-morning weather: Open-Meteo Historical Weather API, weather near the city from 2021 to 2025, updated 2026-10-14. Not official race-day readings.
Guide reviewed . RunWeather is an independent guide, not the race organiser. Dates, waves and routes can change; the organiser’s latest instructions take priority. Course map: The 2023 course from RunWeather's race catalogue. The next edition may differ; elevation is approximate.
Boulogne-Billancourt race morning, on your phone.
Free on iPhone and Android. Your race plan, updated with the forecast until the gun.
On a computer? Scan with your phone camera to get the app.