What's the water temperature at Lucky Peak Reservoir in July?
Guillermo Esteves
May 20, 2025
Ever since the return of Ironman 70.3 Boise was announced, I've been wondering what the water temperature would be like on race day. I know in the previous iterations of this race, when it was in early June, it was a very cold swim: In 2011 the water temperature was 11ºC, and in 2012 it was so cold, people wore wetsuits on the bike, which was shortened to 24 km. So far I haven't been able to find a reliable source of historical water temperatures at Lucky Peak Reservoir to look up what it might be like in late July, but today I got an email from Ironman that states (emphasis mine): The IRONMAN 70.3 Boise 2025 swim course offers athletes a refreshing and scenic 1.2-mile swim in the pristine waters of Lucky Peak Reservoir. Starting and finishing in the easily accessible Barclay Bay area, this single-loop course provides a calm and clear environment, ideal for both seasoned swimmers and first-time triathletes. The reservoir's typical water temperatures in late July range from 64°F to 70°F (18°C to 21°C), making it comfortably wetsuit-legal for most participants. That's not so bad, that's downright pleasant! Anyway, just thought of dropping that here in case anybody else needs to Google it. Update: The water temperature on race day in 2025 was 19.6ºC.
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