St. Lawrence Marathon

Cornwall, ON, Canada · April 24, 2027

42°·54° high·Breezy·Dry

Weather

Race Day Weather

42°at start

55° high

Breezy

Dry

Cool start, steady tailwinds

Runners will face a cool start at 42°F, gradually warming to 55°F. Light winds from the WSW will provide a tailwind for most of the race, particularly beneficial in miles 1-13 and 16-20. With humidity at 53%, adjusting pace conservatively early on is advised to manage the temperature rise, especially through the flat course.

Race day forecast available in 193 days

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Race Info

A Boston-qualifier marathon that follows the St. Lawrence River from Crysler Park Marina to St. Lawrence College in Cornwall, Ontario. Half marathon, 10K, and 5K distances follow the Great Lakes Waterfront Trail along the same stretch of river. The course has a net downhill elevation profile. Source

Website

FAQ

When is the 2027 St. Lawrence Marathon?

The 2027 St. Lawrence Marathon will be held on Saturday April 24, 2027.

Is the St. Lawrence Marathon a Boston Marathon Qualifier?

Yes, the St. Lawrence Marathon is an official Boston Marathon qualifier.

What will the weather be like for the 2027 St. Lawrence Marathon?

The forecast calls for a high of 59°F and a low of 39°F with a 15% chance of rain.

Historical Weather

Based on 6 years of data

Avg Temp

53°F

L:40° H:54°

RunScore

Conditions

Rain Freq

50%

3 of 6 yrs

Wind11mph

Dew35°F

Temperature History

Range of temperatures during race hours for each year.

Detailed History

Year	Low / High	Rain	Dew Point
2026 St. Lawrence Marathon Clear conditions throughout the day. 2026	38°/56°	-	27°
2025 St. Lawrence Marathon Cloudy skies throughout the day with rain. 2025	46°/50°	Light	45°
2024 St. Lawrence Marathon Becoming cloudy in the afternoon with late afternoon rain. 2024	37°/69°	-	30°
2023 St. Lawrence Marathon Partly cloudy throughout the day with rain in the morning and afternoon. 2023	47°/55°	Light	41°
2022 St. Lawrence Marathon Clear conditions throughout the day. 2022	35°/56°	-	23°
2019 St. Lawrence Marathon Partly cloudy throughout the day with a chance of rain throughout the day. 2019	39°/41°	Light	34°

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