Thousand Islands Half Marathon, 10K & 5K

Thousand Islands Half Marathon, 10K & 5K 2026 Course Analysis

Thousand Islands Half Marathon, 10K & 5K is a half marathon held in Wellesley Island, United States of America, scheduled for Friday 15 May 2026. The course is run on road surface with 0m of total elevation gain, reaching a maximum altitude of 0m above sea level. For registration and full race details, visit the official Thousand Islands Half Marathon, 10K & 5K website.

Elevation Profile

This is a very flat course with only 0m of total elevation gain across the full distance. The course ranges from 0m to 0m above sea level — a 0m elevation range that makes it one of the flatter races available. Runners targeting a personal best will appreciate the minimal climbing.

Expected Race Day Weather

Based on historical weather data for May, the expected race day conditions are as follows. Near-ideal running temperatures are expected, ranging from 9°C to 16°C. This temperature range is widely considered optimal for marathon performance, allowing efficient heat dissipation without cold-related issues. There is a moderate chance of rain (21%). Runners may want to prepare for wet conditions but shouldn't expect persistent rainfall.

Surface Type: Road

Thousand Islands Half Marathon, 10K & 5K is run on road surfaces, which provide the fastest and most predictable conditions for marathon running. Road courses allow for consistent pacing and are typically the best choice for runners targeting a personal best time.

How Difficult Is Thousand Islands Half Marathon, 10K & 5K?

Our difficulty rating for Thousand Islands Half Marathon, 10K & 5K is calculated using a model that combines elevation gain, temperature impact, and surface type. Use the difficulty calculator above to enter your target finish time and see exactly how many minutes this course would add or subtract compared to a perfectly flat, cool, road-based half marathon. Faster runners and slower runners are affected differently by the same course conditions, so the difficulty is personalised to your pace.

Looking for an easier marathon or a tougher challenge? You can also compare Thousand Islands Half Marathon, 10K & 5K against other half marathons to find the right race for your goals.