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Triathlon Atlas

Half distance · 12 June 2027

IRONMAN 70.3 Boulder

Boulder, United States

The race at a glance

Official race website
Circuit
IRONMAN
Distance
Middle distance
Terrain
Road
Swim
1.9 km
Bike
90 km
Run
21.1 km
Date
12 Jun 2027
Registration
Open
Swim venue
Reservoir
Average water temperature
17 °C
Bike profile
Hilly
Bike elevation gain
826 m
Run profile
Hilly
Run elevation gain
128 m
High air temperature
33 °C
Low air temperature
13 °C
Overall cut-off
8 h 30 min
Entry fee, from
$440
Altitude
1,579 m
First edition
2010
Swim start
Rolling start

Edition history

202613 Jun 2026Held
202514 Jun 2025Held
20248 Jun 2024Held
202310 Jun 2023Held
20226 Aug 2022Held
20217 Aug 2021Held
20193 Aug 2019Held
20184 Aug 2018Held
20175 Aug 2017Held
201611 Jun 2016Held

How the day is laid out

The swim is held in a reservoir. An average of 17 °C sits in the range where a wetsuit is both allowed and worth wearing for nearly everyone.

The bike leg is labelled hilly and runs over 2 loops.

The run is labelled hilly, over 2 laps.

A hilly bike followed by a hilly run is the hardest combination on the calendar. The bike leg costs more than its distance suggests, and the run asks for what is left afterwards.

Expect air between 13 °C and 33 °C on race day. A spread of 20 degrees across the day matters as much as the peak, because what you wear at the swim exit is rarely what you want at the far end of the bike.

Against the calendar

Where this race sits among the others

Ranks are computed across every race of the same distance.

  • Average water temperature

    17 °C · median 21 °C

    The 8th coldest of the 128 middle-distance races with a figure, across every circuit.

  • High air temperature

    33 °C · median 25 °C

    The 10th hottest of the 152 middle-distance races with a figure, across every circuit.

  • Bike elevation gain

    826 m · median 569 m

    The 32nd hilliest of the 105 middle-distance races with a figure, across every circuit.

3

races of this distance pair a hilly bike with a hilly run, out of 159. 29 share the bike profile alone.

58

races across every distance fall in June, out of 354.

68

races are held in North America. 11 of them in the same month as this one.

Questions about this race

When is IRONMAN 70.3 Boulder 2027?
IRONMAN 70.3 Boulder is held on 12 June 2027 in Boulder, United States. Registration is open on the official race page.
Is a wetsuit allowed at IRONMAN 70.3 Boulder?
Most likely. The average water temperature is 17 °C, below the 24.5 °C limit up to which wetsuits are allowed for age-group athletes. The official call is made on race morning.
What is the cut-off at IRONMAN 70.3 Boulder?
The course closes 8 h 30 min after the start. Intermediate cut-offs after the swim and the bike are in the athlete guide.
How hard is IRONMAN 70.3 Boulder?
The bike course climbs about 826 m, the 32nd hilliest of 105 half-distance races with a figure. The bike is labelled hilly and the run hilly. Expect highs of about 33 °C on race day.
How much is the entry fee for IRONMAN 70.3 Boulder?
Entries start at US$440 for an individual age-group entry, before service fees. Prices rise by tier as the race fills.

Where to stay

Hotels and rentals around the race venue, for the nights around race day.

Suggested stay: 10 Jun 2027 to 13 Jun 2027

The map is provided by Stay22. Bookings are made with the provider.

Races of the same distance in the same region

Entries are handled by the organiser

Registration and the athlete guide are on the official race page.

Open the official race page