The Half Marathon: Flat on Paper, Brutal on the Thermometer

The Course

The run leg of IRONMAN 70.3 Northern California is a two-loop half marathon between the Redding Civic Auditorium, the Sacramento River Trail, and the Sundial Bridge. Total elevation gain: 296 ft over 21.1 km. It's a flat run, period. No climbs to break your rhythm, no descents to trash your quads. The two-loop format lets you mentally split the race and see the crowd multiple times: race reports mention strong local community support in the finish area at the Sundial Bridge.

The Real Opponent: The Temperature

Let's be honest about the data. The official race info lists a high of 31°C, but those numbers come from the 2026 edition, raced in August. On the run course in 2026, temperatures hit around 35°C. The 2027 edition is May 23: it could be noticeably cooler, but there's no historical May data for this race. Practical takeaway: prepare for heat, and if it ends up cool, you've only gained.

The course alternates between shaded and exposed sections. In 2026, the organizers set up cooling stations with ice baths. There's no guarantee they'll be there in 2027, but it's a sign the organizers themselves see heat as a factor.

Pacing: The Blow-Up Starts in the First 5 km

On a flat course after a net-downhill bike, the classic script goes: you roll into T2 with a bike split above expectations, start running at your dream pace, and between km 12 and km 16 the heat hands you the bill.

How to avoid it:

• First 5 km at a controlled heart rate. Set a ceiling in beats, not just a pace. In the heat, pace lies. Your heart rate doesn't.
• Conservative first loop, second loop by feel. With two loops you have a perfect reference: if you feel good at the turnaround, you've got 10 km to push.
• Negative split as the goal, even split as an acceptable reality. A positive split in the heat on a flat course is almost always a pacing error, not a fitness problem.

Ice and Cooling Plan

If conditions are similar to 2026, you need a protocol, not improvisation:

• At every aid station: ice in your cap, water on your neck and wrists.
• If the ice baths are there, use them: a few seconds of cooling are worth more than the time you lose stopping.
• Slow down in exposed sections and pick the pace back up in the shade, instead of holding a rigid pace everywhere.

No experiments on race day: practice running soaked, with ice on you, in training to learn how your shoes and skin react.

Specific Training

Between now and race day, two workouts pay off more than anything else. First: race-pace run blocks during the hot hours of the day, with progressive heat acclimation over the final 2-3 weeks. Second: bike+run bricks where the bike finishes fast (to simulate the net descent) and the run starts deliberately held back. Learn what it feels like to hold yourself back when your legs are spinning.

The Decision to Make

Lock in two numbers now: your max heart rate for the first 5 km and the pace you will NOT exceed on the first loop, no matter what your legs say. Write them down. On race day, with 30 degrees and the Sundial Bridge crowd pushing you, they'll be the only thing standing between you and the wall at km 15.