Training for a fall marathon through the Québec summer

Running 30 kilometres on a Sunday morning in July when the temperature soars to 28 degrees and the humidity is suffocating is a whole different story than training in the fall. The good news is that if you can weather the rigors of summer, you’ll line up at the starting line of your fall marathon with a huge advantage: your body will have learned to perform under challenging conditions, and it will feel light in the cool September air. Here’s how to get through the summer without losing your motivation or your health.

Dealing with heat and humidity

Heat is the number one enemy of the summer endurance runner. When it’s hot and humid, the body has to divert some of its blood to the skin to cool down, which leaves less oxygen for the muscles. The result: your heart rate spikes, your pace slows, and the perceived effort skyrockets—even at a speed you usually find easy.

The most effective strategy is still to choose the right time of day. In Québec, the best times to run in the summer are:

• Early in the morning, between 5:30 a.m. and 8 a.m., when the air is still cool and the humidity is more bearable. This is also the quietest time for your long runs.
• In the evening, after 7:00 p.m., once the sun has gone down and the worst of the heat has passed.
• What to avoid at all costs: the period from 11 a.m. to 4 p.m., when the sun is at its strongest and the risk of heatstroke is highest.

Also keep an eye on the Humidex and Environment Canada’s heat advisories. On days with smog or extreme heat waves, it’s better to switch to a treadmill indoors than to put your health at risk.

Summer hydration and electrolytes

In the summer, you can lose more than a litre of sweat per hour of running. Neglecting hydration quickly leads to decreased performance, cramps, and, in severe cases, heatstroke. It’s not enough to just drink while running—hydration is a year-round commitment.

• Drink water regularly as soon as you wake up and throughout the day, not just around your workouts.
• For any run lasting more than an hour, bring water with you: a hydration belt, jacket, or soft flask are your best allies in the summer.
• Add electrolytes (sodium, potassium, magnesium) to your water during long runs. Sweat isn’t just water, and replacing only the fluid without the minerals can cause problems.
• A simple way to check your hydration: keep an eye on the colour of your urine. Pale yellow is a good sign. If it’s dark, you need to drink more.

To learn more about your fuelling strategy during exercise, check out our guide to hydration and nutrition for runners.

Acclimating to the heat: A real advantage

The human body has a remarkable ability to adapt to heat. By running regularly in hot weather for 10 to 14 days, your body learns to regulate its temperature more effectively: you start sweating earlier and more profusely, your sweat becomes less salty, and your blood volume increases. This is known as heat acclimatization.

This adaptation is invaluable. Not only does it make your summer workouts more bearable, but it also improves your overall performance. Some runners even deliberately seek out the heat as part of their preparation. The key is to take it slowly: reduce your pace and distance during the first few days of a heat wave, then gradually increase them as your body adjusts. Never force a sudden acclimatization—that’s how you get injured or sick.

Adjusting your pace in hot weather

Here’s a classic summer mistake: trying to stick to the paces in your training plan at all costs, even when the thermometer says otherwise. In extreme heat, maintaining the same pace requires much more effort. Trying to stick to a set pace when it’s 30 degrees is a surefire way to run yourself into exhaustion or injury.

Learn to run based on effort rather than time on hot days.

• Slow down by 20 to 40 seconds per kilometre in very hot and humid weather—without feeling guilty. Your actual effort remains the same.
• Rely on your heart rate or how you feel rather than the speed displayed on your watch.
• Save your high-intensity workouts (intervals, threshold) for cooler days or the mildest times of day.
• Remember that a slow run in extreme heat provides a training stimulus equivalent to a faster run in cooler conditions.

This flexibility is an integral part of a good marathon training plan. A plan is a guide, not a law set in stone.

Sun protection, mosquitoes, and terrain

Québec summers bring their share of nuisances beyond just the heat. First, the sun: a long run without protection can lead to a nasty sunburn or even heatstroke. Apply water-resistant sunscreen, wear a cap or visor, and sunglasses. UV-protective running clothes are also a good option.

Next, mosquitoes and black flies can quickly turn a run in the woods into a nightmare, especially in June and July. If you’re running on trails or near water, insect repellent can save your run. In fact, many runners prefer open, windy routes in the summer to avoid these pests.

When it comes to terrain, opt for shaded routes along rivers, tree-lined bike paths, or large parks. Shade makes a significant difference in how hot it feels. Also, locate drinking water sources along your route—they become invaluable during heat waves.

Planning long runs in the summer

Long runs are the cornerstone of marathon training, and they’re also the trickiest to manage in the summer. Running for two or three hours in the heat requires careful planning.

• Set out as early as possible—ideally at dawn—to finish before the heat sets in.
• Choose a loop or out-and-back route that brings you back near your starting point, or hide water bottles along the way.
• Let a loved one know your route and bring your phone. Dehydration can strike quickly and severely.
• Bring enough supplies to keep you fuelled: energy gels, electrolytes, and plenty of water. This is also the perfect opportunity to test your race nutrition strategy.
• If the heat becomes too intense partway through your run, don’t hesitate to shorten or break up your session. It’s better to adjust your run than to quit entirely or feel unwell.

The advantage of running in the cool fall weather

Here’s the reward for all that summer training. After sweating for weeks while dragging your body through the July humidity, imagine how it will feel on the morning of your fall marathon: 12 degrees, dry air, blue skies. Your body, accustomed to performing under much tougher conditions, will literally feel liberated.

Physiologically, running in cool weather allows you to maintain a lower heart rate at the same pace, better regulate your body temperature, and delay fatigue. Paces that seemed grueling in the summer suddenly become manageable. This is one of the great secrets of Québec runners: a summer of training in the heat sets the stage for a fall of peak performance. You’ve put in the work—now all that’s left is to reap the rewards.

The transition to cooler temperatures

As September approaches and your target race draws nearer, the mornings start to cool down. This transition is the perfect time to fine-tune your preparation and adjust a few details.

• Take advantage of the cooler days to test your target marathon paces. You’ll finally see what you’re truly capable of, without the heat holding you back.
• Gradually reintroduce quality workouts at specific paces, now that conditions allow it.
• Adjust your wardrobe: Fall mornings can be cool at the start but mild by the finish. Think about thin layers you can remove and clothing for cooler days.
• Reassess your hydration: your needs decrease as temperatures drop, but don’t neglect them entirely.

This phase often coincides with tapering—those last two or three weeks when you reduce your training volume to arrive fresh and ready on race day.

Summer gear for marathon runners

The right gear makes a real difference when it comes to getting through summer training. Here are the essentials to gather before tackling your heaviest training weeks.

• Lightweight, breathable technical clothing in light colours that wicks away sweat and reflects the sun. Avoid cotton, which stays soggy.
• A hydration belt or vest to carry water and electrolytes on long runs.
• A cap or visor, sunglasses, and sweat-resistant sunscreen.
• Anti-blister socks, since sweat and friction take a toll on long summer runs.
• An anti-chafing balm for sensitive areas: groin, armpits, nipples. Heat makes irritation worse.
• A GPS watch with a heart rate monitor, which is invaluable for running based on effort rather than time in hot weather.

Conclusion

Preparing for a fall marathon during the Québec summer means accepting that you’ll have to endure the heat and humidity now to reap the rewards in the cool September air. By running early in the morning or in the evening, staying well-hydrated, acclimating gradually, and adjusting your pace to the conditions, you’ll get through the summer in good health and arrive at the starting line better prepared than ever. The secret isn’t to fight the summer, but to deal with it wisely. Ready to pick your goal? Check out the fall marathons in Québec and browse the Québec race calendar to find the event that will get your heart racing this fall.