Tamarack Ottawa Marathon
Ottawa, Canada · Last Sunday of May
Canada's most prestigious marathon sweeps along the Ottawa River and Rideau Canal parkways with Parliament Hill and the National War Memorial as backdrop. The course is flat and fast, earning consistent World Athletics Label status, and the early 7am start optimises conditions before the late-May sun climbs. Part of the massive Tamarack Ottawa Race Weekend (50,000+ runners across all distances), the race has an exceptional atmosphere — though accommodation sells out months in advance.
Course
Elevation gain
120 m
Net elevation
-10 m
Finishers
~4,500
Month
May
Last Sunday of May
Race-day weather
Median start temp
14°C
Historical range
8–22°C
Hot-year risk
Moderate
Ottawa in late May averages 11–14°C at the 7am gun — ideal conditions — but roughly 1 in 5 years sees a 25°C+ afternoon. The 2016 edition reached 28°C with a 39°C humidex, forcing course modifications and hospitalizations. Weather is the biggest variable on an otherwise PR-friendly course.
Getting in
Sells out fast. First-come, first-served via runottawa.ca; opens October–November for the May race and sells out within days to weeks. No lottery. Part of the 50,000-runner Tamarack Ottawa Race Weekend — book accommodation months in advance, the city fills completely. Official site ↗
Pacing plans for Tamarack Ottawa Marathon
Course-adjusted splits for every common goal — not flat even splits, but pacing that matches where this course is fast and where it bites.
Frequently asked questions
Is the Tamarack Ottawa Marathon a fast course?
Yes, it is a fast course by big-marathon standards. The course has 120 m of total elevation gain. We rate it 8/10 for PR potential.
What is the weather usually like at the Tamarack Ottawa Marathon?
The median start-line temperature is around 14°C, with a historical range of roughly 8–22°C. Ottawa in late May averages 11–14°C at the 7am gun — ideal conditions — but roughly 1 in 5 years sees a 25°C+ afternoon. The 2016 edition reached 28°C with a 39°C humidex, forcing course modifications and hospitalizations. Weather is the biggest variable on an otherwise PR-friendly course.
How do you get into the Tamarack Ottawa Marathon?
Sells out fast. First-come, first-served via runottawa.ca; opens October–November for the May race and sells out within days to weeks. No lottery. Part of the 50,000-runner Tamarack Ottawa Race Weekend — book accommodation months in advance, the city fills completely.
Is the Tamarack Ottawa Marathon a Boston qualifier?
Yes — the Tamarack Ottawa Marathon is a certified course accepted by the B.A.A. for Boston qualifying times.