IRONMAN 70.3 Westfriesland
Course breakdown, historical weather, and field analysis.
Dutch flat-course racing — polders, wind, and pure power
· June 21, 2026
IRONMAN 70.3 Westfriesland in the Netherlands offers one of the flattest 70.3 courses in the world. A lake swim, a pan-flat bike through the Dutch polders, and a flat run through the Westfriesland countryside. If you like flat-and-fast racing where wind is the only variable, this is your race.
- Swim
- 1.9 km
- Lake
- Bike
- 91.6 km
- ↑55m · Flat
- Run
- 21.2 km
- ↑6m · Flat
- Air Temp
- 12–30°C
- Water Temp
- 17°C
- Wind
- 17 km/h
- S
Swim Course
Lake swim in the Dutch countryside
The swim takes place in a lake in the Westfriesland region. Dutch lake conditions provide calm, freshwater swimming. Water temperatures vary depending on the season. The flat surrounding landscape means the lake is well-exposed, and wind can create surface chop.
- Calm freshwater lake swim
- Flat Dutch countryside setting
- Wind chop possible on windy days
- Straightforward navigation
Bike Course
Polder flat — Dutch roads and Dutch wind
The bike course is quintessentially Dutch: pan-flat polder roads through the countryside with zero climbing. The challenge is entirely wind-driven — the open, flat landscape offers absolutely no shelter, and the North Sea influence means wind is almost always present. This is a pure aerodynamics test where CdA and steady power output matter more than climbing ability. Deep-section wheels are powerful here in light winds but risky in strong crosswinds on the exposed polders.
- Pan-flat polder roads — zero climbing
- Wind is the only variable and it's always present
- Pure aerodynamics test — CdA matters most here
- No shelter on the open Dutch landscape
Run Course
Flat run through the Westfriesland countryside
The run continues the flat theme through the Westfriesland countryside. The terrain is completely flat, making this a fast course for well-paced athletes. Dutch wind remains a factor even on the run. The local Dutch community provides enthusiastic support.
- Completely flat running course
- Wind remains a factor even on the run
- Dutch community support
- PB potential on a fast flat course
Race Day Conditions
Dutch summer — mild, breezy, and potentially wet
The Dutch climate offers mild temperatures with wind as the constant companion. Air temperatures range from 12–20°C with variable cloud cover and the ever-present possibility of showers. The North Sea influence keeps temperatures moderate but ensures wind is always a factor. Athletes should prepare for conditions that can change rapidly.
Race Field Insights
How the Field Performs
Aggregated from 6,534 finishers (2021–2025)
- Total Starters
- 6,798
- Finishers
- 6,534
- DNF Rate
- 3.6%
- Years of Data
- 2021–2025
- Median Finish
- 5h 37m
Finish Time Distribution
How the Median Finisher Spends Race Day
What Each Pace Looks Like
Fast | Solid | Median | Back of Pack | Slow (P90) | |
|---|---|---|---|---|---|
| Swim | 31m 59s | 35m 32s | 39m 52s | 44m 11s | 48m 58s |
| Bike | 2h 24m | 2h 33m | 2h 44m | 2h 58m | 3h 12m |
| Run | 1h 36m | 1h 46m | 1h 58m | 2h 14m | 2h 31m |
| Finish | 4h 46m | 5h 08m | 5h 37m | 6h 07m | 6h 42m |
Plan IRONMAN 70.3 Westfriesland with Keiro
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Independent analysis. KeiroLabs is not the event organizer and is not affiliated with the race organizer.