IRONMAN 70.3 Oceanside
Course breakdown, historical weather, and field analysis.
Southern California's season opener — fast, flat, and ocean-swept
Oceanside, United States · March 28, 2026
IRONMAN 70.3 Oceanside kicks off the North American 70.3 season on the Southern California coast. An ocean swim at Oceanside Harbor, a rolling out-and-back bike through Camp Pendleton, and a flat run along the coast. With its late March date and proximity to San Diego, this is one of the most popular early-season 70.3s on the circuit.
- Swim
- 1.9 km
- Ocean
- Bike
- 90.5 km
- ↑746m · Rolling
- Run
- 21.5 km
- ↑114m · Rolling
- Air Temp
- 5–20°C
- Water Temp
- 15°C
- Wind
- 9 km/h
- SE
Swim Course
Harbor swim in the protected waters of Oceanside
The 1.9 km swim takes place in Oceanside Harbor — a protected inlet that avoids the open Pacific Ocean swell. Water temperatures in late March typically sit around 15–17°C, making this a wetsuit-legal and chilly swim. The calm harbor conditions make it accessible, though the water can be murky. A rolling start spreads the field and reduces contact.
- Protected harbor swim — no open ocean swell
- Wetsuit-legal at 15–17°C — neoprene warmth essential
- Rolling start in calm conditions
- Murky water possible — sighting on buoys is important
Bike Course
Rolling out-and-back through Camp Pendleton
The 90 km bike course heads north through the Marine Corps Base Camp Pendleton on a rolling out-and-back route. The terrain features moderate climbs and fast descents with exposed sections that catch Pacific coastal wind. The road surface through the base is generally good. The rolling profile rewards athletes who can modulate power — pushing the climbs hard and recovering on the descents is more efficient than riding a constant effort.
- Out-and-back through Camp Pendleton Marine base
- Rolling terrain with moderate climbs
- Exposed coastal sections with potential headwind on the return
- Good road surfaces through the military base
Run Course
Flat coastal run along the Oceanside strand
The two-lap run course follows the flat coastal strand through Oceanside. The terrain is almost entirely flat, making it a PB-friendly course for runners who pace their bike correctly. The Pacific breeze keeps temperatures comfortable in late March, and spectator support along the beachfront is strong. The two-lap format gives athletes and supporters multiple touchpoints.
- Flat coastal course — PB potential for well-paced athletes
- Pacific breeze keeps temperatures comfortable
- Two laps with beachfront spectator support
- Late March conditions are typically mild and dry
Race Day Conditions
Mild Southern California spring — comfortable racing
Late March in Oceanside offers comfortable racing conditions. Air temperatures range from 12–20°C, with morning chill at the swim start warming to pleasant midday temperatures. Pacific winds can pick up through the day, particularly on the exposed bike course sections through Camp Pendleton. Rain is unlikely but possible. The main weather consideration is the cool water temperature — a good wetsuit is essential.
Race Field Insights
How the Field Performs
Aggregated from 11,016 finishers (2021–2025)
- Total Starters
- 12,361
- Finishers
- 11,016
- DNF Rate
- 7.1%
- Years of Data
- 2021–2025
- Median Finish
- 6h 13m
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 26s | 35m 40s | 40m 30s | 45m 34s | 51m 22s |
| Bike | 2h 39m | 2h 53m | 3h 10m | 3h 30m | 3h 49m |
| Run | 1h 35m | 1h 48m | 2h 04m | 2h 24m | 2h 43m |
| Finish | 5h 00m | 5h 33m | 6h 13m | 6h 56m | 7h 37m |
Plan IRONMAN 70.3 Oceanside with Keiro
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Independent analysis. KeiroLabs is not the event organizer and is not affiliated with the race organizer.