Extreme heat: What happens to your body when temperatures reach 40°C?

Extreme heat makes the body work harder to maintain a stable internal temperature.

If the body cannot cool itself effectively, it increases the risk of serious heat-related illness.

The South African Weather Service (SAWS) has warned of very hot to extremely hot and uncomfortable conditions.

Temperatures of between 36°C and 40°C expected in parts of the Namakwa District in the Northern Cape and the interior of the Western Cape.

The World Health Organization (WHO) warns that extreme heat can increase the risk of heat exhaustion, heatstroke and complications linked to existing health conditions.

How extreme heat affects your body

The human body normally maintains an internal temperature of around 37°C.

When surrounding temperatures rise, it relies mainly on sweating and increased blood flow to the skin to release excess heat.

Heavy sweating also causes the body to lose water and salts.

Without enough fluids, a person can become dehydrated, experience headaches and dizziness, and develop muscle cramps.

The heart also has to work harder as it pumps more blood towards the skin to help release heat.

This can place additional pressure on people with existing heart conditions.

Extreme heat can also affect the kidneys and worsen existing health problems, including respiratory illnesses, diabetes and cardiovascular disease.

When does heat become dangerous?

Heat exhaustion occurs when the body loses too much water and salt through sweating. Symptoms can include:

• Heavy sweating
• Headaches
• Dizziness or faintness
• Weakness and tiredness
• Nausea
• Muscle cramps
• A rapid heartbeat

Who faces the greatest risk?

Extreme heat can affect anyone, but some people face a greater risk of becoming seriously ill.

These include:

• Older people, particularly those over 65
• Babies and young children
• Outdoor workers and people who exercise in hot conditions
• People with heart, lung or kidney conditions
• People living with disabilities
• Those who live alone or do not have access to cool spaces

How to protect yourself during extreme heat

The WHO recommends taking practical steps to reduce exposure and help the body stay cool.

• Avoid strenuous outdoor activities during the hottest part of the day.
• Stay in the shade or spend time in a cool indoor space.
• Drink water regularly, even if you do not feel thirsty.
• Wear light, loose-fitting clothing.
• Take cool showers or use a damp cloth to cool your skin.
• Close blinds or curtains during the day to keep direct sunlight out of your home.
• Open windows at night when outdoor temperatures are lower than indoor temperatures.
• Check regularly on older people, children and anyone with a health condition.

As temperatures climb towards 40°C, taking precautions early can help prevent heat-related illness.

People should also follow official weather updates and seek medical help if they develop serious symptoms.