Boulder Reservoir
Leave the water with your day still quiet.
The reservoir's calm, current-free water rewards an honest, controlled opening rather than fighting for position.
Seed honestly. Settle into rhythm.
Race Finder IRONMAN 70.3 Boulder.
Race Intelligence · Boulder, United States
IRONMAN 70.3 Boulder.
Your best day in Boulder.
One loop in Boulder Reservoir. Two bike laps on the roads north of town. Two more laps on foot around the reservoir, road and packed dirt.
Boulder, the Flatirons mountains.
- Race day
- 12 Jun 2027
- Course
- Swim 1.9 km · Bike 90 km · Run 21.1 km
- Historical air
- 12–29°C
Your day in Boulder
What could you race?
I’m Tom, the coach behind Sense Endurance Coaching. Tell me where you are now and I’ll show you what a strong day in Boulder could look like.
The course behind your race
Boulder gives you the same question twice.
Both long legs repeat themselves. The first bike lap should set an effort you are willing to see again, and the first run lap should leave enough control to race the second.
Bike lap one · north of Boulder
Choose the effort you are prepared to repeat.
The short rollers toward Hygiene Road and the fast descent back feel easy on a fresh first lap. Hold the effort you can repeat.
Cap opening effort. Fuel early.
Bike lap two · back to the reservoir
Repeat the discipline, not the excitement.
The second lap is identical terrain on tired legs. Match the first lap's effort rather than letting it drift.
Stay patient. Finish planned nutrition.
Reservoir dam and Monarch Road · first loop
Let the surface change without forcing the pace.
Let the packed-dirt rollers along Monarch Road feel easy, not fast.
Easy first aid station. Check posture.
Second run loop
Race only after the first loop has stayed together.
Only progress once the first lap has held together.
Stay tall. Choose the last move late.
What to check in race week
Confirm the latest reservoir swim layout, bike-lap turns, aid locations and the condition of the packed-dirt run sections. Decide in advance what power and breathing should look like on lap one so that lap two is a repeat rather than a rescue.
Forecast statusToo early for a forecast
A race-day forecast is not meaningful yet; check back closer to the event.
- Temperature
- 12.4–28.9°CDew point centred on 7.5°C
- Wind and gusts
- 6.7 km/hGusts up to 34.2 km/hPrevailing direction E
- Rain likelihood
- Up to 65%Wet-surface uncertainty retained
Historical baseline, 2019–2025 · Open-Meteo historical archive · Updated 2026-09-14.Historical comparison only. This is not a forecast for 2027.
Make your finish prediction and I can send this plan to you in race week.
Your plan, in race week
Prepare for Boulder
Build the legs.
Practise the decisions.
A finish range gives you something to work towards. The preparation is specific to this race: Train repeatability: steady power over short rollers, fuelling on a schedule and running smoothly when the surface changes. Boulder rewards the athlete who can make the second lap look like the first without needing the same speed.
I’m Tom. With Sense Endurance Coaching, I’ll build that preparation around your life, follow how you respond and adjust the work as you get closer to Boulder.
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