Yes, you can still train in a heatwave, but you’ll want to dial it back. Once temperatures push past 25-30°C, your body works a lot harder to stay cool. That doesn’t mean you have to stop moving. It just means choosing gentler sessions, better timing, and paying closer attention to how you feel. Below we cover the real risks of training in the heat, which workouts to avoid, and how to stay active without putting yourself in danger.
Why training in extreme heat carries real risks
Exercising when it’s hot asks far more of your body than most people realise. On a warm day you’re likely to notice:
- A higher heart rate: your body works harder to shed heat, so your pulse climbs faster than usual.
- More fluid loss: extra sweating means you lose more water and important minerals.
- A greater chance of dehydration: drinking too little can leave you with headaches, dizziness and fatigue.
- Weaker performance: your body spends energy cooling itself, so you often can’t go as hard or as long.
- Risk of heat exhaustion: nausea, muscle cramps and heavy fatigue can set in.
- Risk of heatstroke: a serious situation where your body can no longer regulate its own temperature.
That’s why it’s sensible to adjust your training as soon as the mercury heads towards 30°C and beyond. A session that normally feels easy can suddenly feel far heavier in the heat.
A simple guide by temperature
- Up to 25°C: train as normal.
- 25-30°C: lower the intensity.
- 30-35°C: stick to easy sessions only.
- 35°C and above: avoid hard efforts altogether.
Can you still train at 35°C?
You can, but adapting your session is the smart move. A tough interval workout, a football match or a long steady run in the middle of the day is usually a bad idea. Instead, pick activities where your body is less likely to overheat. Good options in a heatwave include:
- An easy steady run: slow the pace right down and aim for early morning or late evening.
- Walking: a walk in the shade is a safe way to stay active without overloading your body.
- Cycling in the morning: the breeze from riding often makes cycling feel more comfortable than running, especially before the heat peaks.
- Swimming: one of the best options in warm weather, because the water keeps cooling you the whole time.
- Strength training in an air-conditioned gym: go a touch lighter than usual and take longer rests between sets.
Not sure whether to head out? Listen to your body. If even the warm-up feels unusually hard, or you notice dizziness, nausea or a headache, stop straight away and get somewhere cool.
What’s best to avoid
Not every workout suits a very hot day. Some efforts add so much extra strain that the risks climb quickly. When temperatures approach 35°C, it’s worth postponing or adjusting the following:
- HIIT sessions: short, explosive efforts spike your body temperature and heart rate fast.
- HYROX-style workouts: the mix of running and intense stations makes this one of the hardest things to do in the heat.
- Long midday runs: between noon and 5pm the risk of overheating is at its highest.
- Football in full sun: lots of sprinting, little shade and few breaks make it especially demanding.
- Training without enough water: fluid loss happens much faster in the heat, so dehydration creeps up on you.
Skipping or moving a session is sometimes the wisest choice. Your fitness won’t vanish over a single rest day, whereas the effects of overheating or dehydration can be genuinely serious.
10 tips for training in warm weather
Want to keep exercising despite the heat? These practical tips lower the chance of overheating so you can stay active safely.
- Train early: between sunrise and around 10am it’s often still relatively cool.
- Drink beforehand: don’t wait until you’re thirsty; start your session already well hydrated.
- Wear light clothing: choose breathable kit that lets heat escape.
- Find shade: run or ride through wooded areas or sheltered spots where you can.
- Adjust your pace: don’t expect the same numbers as on a cool day, and ease off the intensity.
- Take extra breaks: plan more short pauses to cool down and drink.
- Use a sports drink on long sessions: for efforts over an hour, it can help top up fluids and electrolytes.
- Listen to your body: if you feel weak, dizzy or very tired, back off immediately.
- Avoid the midday hours: between noon and 5pm the sun is strongest and temperatures usually peak.
- Stop at the first sign of dizziness or nausea: these can be warnings that your body is struggling to cool down.
A few simple tweaks let you keep moving safely, even in warm weather. The main thing to remember is that your health always comes before your training plan.
Do any supplements help in the heat?
Supplements aren’t a magic fix, but a few can help you take in enough fluid and minerals on hot days, especially if you’re training for longer than an hour or sweating heavily. An electrolyte tab or a sports drink replaces sodium and other minerals lost through sweat, which can make a difference on long sessions. Most people doing ordinary training in the heat will do fine with plain water and a balanced diet. If you do want something extra, a basic electrolyte product is inexpensive and does the job without any need for fancier options.
Frequently asked questions
Is it safe to run when it's 35°C outside?
You can run, but keep it easy and choose your timing carefully. Avoid long or hard runs in the middle of the day, slow your pace right down, and head out early morning or late evening when it’s cooler. If you feel dizzy or unusually tired, stop and find shade.
How do I know if I'm overheating during exercise?
Warning signs include feeling faint or dizzy, nausea, a headache, muscle cramps, and a warm-up that suddenly feels far harder than normal. If any of these show up, stop straight away, get somewhere cool and drink. Ignoring them can lead to heat exhaustion or heatstroke.
What are the best workouts in a heatwave?
Swimming is one of the best, because the water keeps cooling you. Easy steady runs, walks in the shade, morning cycling, and lighter strength sessions in an air-conditioned gym are all good options. The idea is to pick activities where your body is less likely to overheat.
Should I skip training altogether when it's very hot?
Sometimes yes. Postponing or moving a session is often the smart choice on the hottest days. You won’t lose fitness over a single rest day, but overheating and dehydration can be genuinely serious, so there’s no shame in taking a break.
Do I need electrolyte supplements in warm weather?
Not always. For ordinary sessions, plain water and a balanced diet are usually enough. If you’re training for more than an hour or sweating heavily, an electrolyte tab or sports drink can help replace the sodium and minerals you lose through sweat. A basic product is cheap and does the job.
What time of day is best to exercise in the heat?
Early morning, roughly between sunrise and 10am, is usually the coolest window. Late evening also works. Try to avoid noon to 5pm, when the sun is strongest and temperatures peak.
