The sun's out, the temperatures are soaring, and your training plan isn't going anywhere. But running in the heat is a whole different challenge, and pushing on as normal can quickly leave you feeling wiped out, underperforming, or worse, putting your health at risk.
The good news? With a few smart adjustments, you can keep training effectively all summer long. Here are five tips to help you run well when the heat is on - whether you're a complete beginner or mid-way through a training block.
1. Run to Effort, Not Pace
This is the most important thing to get your head around when running in the heat. When temperatures hit around 30°C, your body is working significantly harder just to keep itself cool, meaning the same effort that felt comfortable last week will now feel considerably harder, and your pace will naturally be slower. That is completely normal and expected, so don't chase your usual numbers.
Think back to what we know about Zone 2 and easy running - the same principle applies here. Trust your effort and your breath over what's on your watch. If you can hold a full conversation, you're at the right intensity, regardless of what your pace says.
It's also worth knowing that your body does adapt to heat over time; but it takes around 10–14 days of consistent exposure before you'll notice a real difference in how manageable it feels. So if a heatwave hits suddenly, give yourself grace in those first couple of weeks and dial back the intensity accordingly. Your watch doesn't know it's hot, but you sure will.
2. Time It Right and Choose Your Route Wisely
When you run matters just as much as how you run. The hottest part of the day is typically between 11am and 4.30pm, so shifting your runs to early morning or evening can make a significant difference to how your session feels and how safely you can complete it.
Route choice matters too. Tarmac and concrete absorb heat throughout the day and radiate it back out, which means running on roads can feel considerably hotter than the air temperature alone suggests. If you can, swap the road for trail running in shade or woodland, which naturally stays cooler. And if the heat is really extreme, there is absolutely no shame in jumping on a treadmill in an air-conditioned gym. Getting the session done safely is always the priority.
Humidity matters just as much as temperature; on a humid day your sweat can't evaporate properly, making it feel considerably hotter and harder than the thermometer suggests. Check the 'feels like' temperature on your weather app before heading out.
3. Sort Your Kit Before You Head Out
What you wear in the heat can make a surprisingly big difference to how you feel. Go for loose, lightweight, breathable fabrics that allow airflow and help sweat to evaporate - this is your body's main cooling mechanism, so you want to support it, not block it.
Colour matters more than you might think too; lighter colours absorb less heat from the sun than darker ones, so save the black kit for cooler days.
A breathable cap and sunglasses are a genuine must, not just for comfort but for protecting yourself from sun exposure during longer efforts. And please, don't skip the suncream. UV levels are high when you're out for an extended period, and sweat will take most high-street products straight into your eyes. Opt for a sports-specific formula or an all-day barrier cream which bonds to the skin and stays put even when you're sweating.
4. Hydration Is Non-Negotiable
Staying on top of hydration in the heat isn't just about drinking during your run; it starts long before you head out. If you arrive at your session already even mildly dehydrated, your body's ability to sweat and cool itself is already compromised, and your performance will suffer from the very first mile.
Drink consistently throughout the day, not just in the hour before your run. A practical trick: pop a few ice cubes in your water bottle before you head out so your drink stays cool for longer - it makes a real difference on a hot day.
During and after your run, don't just replace fluid, replace electrolytes too. When you sweat heavily, you lose sodium and other minerals that play a key role in keeping your muscles working properly and your fluid balance in check. A sports drink, electrolyte tablet, or even a salty snack post-run all help here.
Finally, the heat can kill your appetite, but don't let it derail your fuelling. Arriving at a session under-fuelled, or skipping your recovery nutrition afterwards, will catch up with you quickly, especially if you're in a training block. Keep it simple and easy to stomach if needed, but keep it consistent.
5. Be Willing to Adapt - This Is Still Good Training!
A shorter, easier session in the heat can be just as valuable as a longer one in cooler conditions, don't write it off just because the numbers look different. If your usual 10K feels like a half marathon today, it probably is the equivalent physiologically. Respect that.
Keep the majority of your runs at low intensity during a heatwave, save any harder sessions for the coolest part of the day, and be willing to cut a session short if you feel dizzy, nauseous, or your heart rate is running unusually high. No single run is worth your health, and consistency over time is always more important than one heroic effort in difficult conditions.
If you're running alone in extreme heat, let someone know your route and estimated time as a sensible precaution when conditions are tough.
Running in the heat is genuinely hard. But approach it smartly and it can be a great opportunity to build mental toughness, practice running by effort, and come out the other side as a more well-rounded runner.
FAQ
Q: How much slower should I expect to run in the heat?
A: It varies by individual and conditions, but in temperatures around 30°C it's common to run noticeably slower at the same effort level by a noticeable amount. Don't fight it: slow down, run to effort, and trust that your fitness is still there when the temperatures drop.
Q: Should I still do speed sessions during a heatwave?
A: If possible, save harder sessions for the early morning or evening when it's coolest, or even once the heatwave has passed if it is a brief one. If the heat is extreme, it's perfectly reasonable to swap a speed session for an easy run and make up the harder effort later in the week. Staying healthy and consistent is more important than sticking rigidly to a plan.
Q: How do I know if I'm getting too hot on a run?
A: Warning signs include dizziness, nausea, a sudden drop in sweat despite feeling very hot, confusion, or an unusually elevated heart rate that won't settle. If any of these occur, stop, move to shade, and rehydrate. Don't push through: heat exhaustion is serious and can escalate quickly.
Q: Do I need to eat differently when running in the heat?
A: Focus on staying hydrated and keeping electrolytes topped up. Your appetite may drop in the heat, but try to stick to your usual pre- and post-run fuelling routine as closely as possible. Light, easy-to-digest foods work well; the key is not skipping recovery nutrition even when you don't feel hungry.
Q: Should I drink more water than usual when running in the heat?
A: Yes, but don't just increase water intake, increase electrolytes too. Drinking large amounts of plain water without replacing sodium and minerals lost through sweat can actually cause a condition called hyponatraemia, where sodium levels drop dangerously low. Sports drinks, electrolyte tablets, or salty snacks alongside your water are the smarter approach on hot days.
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