Tamarack Ottawa International Marathon
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May 30, 2027
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The Tamarack Ottawa International Marathon is the main race of Ottawa Race Weekend, held on a Sunday at the end of May and organised by the not-for-profit Run Ottawa. The marathon starts at 7:00am at Ottawa City Hall on Laurier Avenue West, and the marathon and half marathon routes both start and finish at City Hall. The organisers describe the routes as flat and fast, past landmarks including the National War Memorial, Dow's Lake, the Dominion Observatory and the Rideau Canal. The course takes runners across the river between Ottawa, Ontario and Gatineau, Quebec. Marathon participants are expected to finish within 7 hours, with a cut-off at the 27 km marker near the Pretoria Bridge at 11:30am. The marathon is a World Athletics Elite Label road race with a certified course, and a Boston Marathon qualifying event; entries are capped at 6,000. The weekend also includes a half marathon on the Sunday and a 10K, 5K, 2K and kids' marathon on the Saturday. The first Ottawa Marathon was held in 1975.
Typical climate for the race month — an estimate, not a forecast or a race-day record
Late May in Ottawa is mild: average highs are about 20°C and lows about 7.5°C, with measurable rain on around 13 days of the month. The 7:00am start is in the coolest part of the day.
The Race
Ottawa
The first Ottawa Marathon was held in 1975. It grew into a race weekend described as the largest marathon event in Canada, with the marathon, half marathon, 10K, 5K and shorter races all starting and finishing at Ottawa City Hall. In 2012 Tamarack Homes became title sponsor and the event took the Tamarack Ottawa Race Weekend name.
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