Strive

Running in summer heat: a Highveld and coastal guide

Thin air in Joburg, wet air in Durban, thunderstorms at four. How to keep training through a South African summer without cooking yourself.

, 3 minute read

A runner on a sandy track on a bright day

A South African summer is great for being outside and hard on running. Depending on where you live, you're dealing with some mix of strong sun, heat, humidity, altitude and afternoon storms. None of these mean you have to stop. They mean you have to adjust.

Accept that you'll be slower

This is the most important adjustment, and the one people resist. Running in heat makes your heart work harder at the same pace, because your body is pushing blood to the skin to cool down as well as to your legs. Humidity makes it worse, because sweat doesn't evaporate and cool you as well.

So run by effort, not pace. If an easy run normally feels like you could chat, keep it at that feeling, even if your watch says you're a minute per kilometre slower. Your fitness still improves.

Time it right

  • Early is best. The hour around sunrise is the coolest part of the day, and in December that's before 06:00 in most of the country.
  • Evenings can work, but pavements and tar hold heat for hours after sunset.
  • Midday is for the treadmill or a rest day.

Where you live changes the problem

Highveld

Johannesburg and Pretoria sit high up; Joburg is roughly 1,750 m above sea level. The air holds less oxygen, so efforts feel harder than the same pace at the coast. The heat is usually dry, which helps, but the sun is fierce at that altitude.

Summer on the Highveld also means afternoon thunderstorms. They build fast. If you hear thunder, you're close enough to be struck by lightning. Get indoors or into a car and wait it out rather than finishing the loop.

Coast

Durban and the KZN coast bring humidity, often high enough that sweat just sits on your skin. Hydration matters more here, and so does slowing down. Cape Town is cooler but windy; the south-easter can make an out-and-back very lopsided, so start into the wind and let it bring you home.

Drink and salt

You don't need to carry water on a short run, but drink properly beforehand. For anything over about an hour, or any run in serious heat, take water with you or plan a route past a tap or garage. On long, sweaty runs, something with electrolytes helps replace the salt you lose. White salt crust on your cap afterwards is a hint you're a salty sweater.

Dress for it

  • Light-coloured, loose, technical fabrics that wick sweat. Cotton gets heavy and stays wet.
  • A cap or visor, sunglasses and sunscreen, every time. Re-apply on long runs.
  • Lube on anywhere that chafes. Heat and sweat make chafing far worse.

Know the warning signs

Heat illness can creep up, and the early signs are easy to ignore when you're determined to finish:

  • headache, dizziness or feeling faint
  • nausea
  • cramps
  • goosebumps or feeling cold while hot
  • unusual tiredness or weakness

If you feel any of these, stop, get into shade, drink, and cool down. Don't push on to finish the route.

Build up gradually

Your body adapts to heat over about one to two weeks of regular exposure. The first hot runs of the season are always the worst. Keep them short and easy, and they'll start to feel normal.