Australia is bracing for another intense heatwave in January, with soaring temperatures set to sweep across multiple states. While summer heat is nothing new, the extremity and frequency of the heat is. And extreme temperatures raise an important question: how hot is actually too hot to go outside?

As we head towards summer's peak, and heatwaves become stronger and more frequent, understanding the impacts of souring temperatures on your body is more important than ever. From weekend plans to what you wear (or don’t), extreme heat reshapes how we move through the world. Here's what you need to know ahead of this weekend's heatwave.

What temperature is considered “too hot” to be outside?

It’s not just the temperature that matters. Factors like UV levels, humidity and wind all affect how hot it feels.

Generally speaking, if the humidity is high, temperatures above 32 degrees Celsius can be considered too hot, while in dry heat, this rises to 40 degrees celsius.

The negative impact of heat can also be viewed through the wet-bulb temperature – a metric that combines heat and humidity. At 35 degrees, the body can fail to cool itself which increases the risk of mortality.

On high-humidity days, sweat evaporates at a slower rate, making it harder for the body to cool itself, and raising the risk of heat exhaustion and heatstroke even faster as a result.

Dangerous temperature levels can vary from person to person, the best way to judge if you're too hot is simply how you feel. When you begin to feel uncomfortable, this is your sign to move somewhere cool.

What happens when your body is "too hot"?

Heatstroke and sunstroke are the obvious consequences of extreme heat when the body is unable to cool itself. These are serious conditions that can go beyond nausea and actually end up fatal. Headaches, muscle cramps, rapid heartbeat and confusion can all be signs of heat-related illness. If you suspect you might be suffering from heatstroke, you should call 000 immediately.

But there are other less immediate problems that can come from extreme heat. Asthma and respiratory issues can be exacerbated. The risk of renal conditions and likelihood of developing UTIs increases. Ear health conditions like ear infections are more likely. Additionally, cognitive ability can be impacted as extreme heat reduces oxygen flow to the brain – this can increase stress, slow processing, increase fatigue and impair memory and judgement.

What about your pets?

Our pets can be more sensitive to extreme heat than us. Experts agree that if the temperature is above 25 degrees celsius, you should test the pavement with the palm of your hand to determine if it is too hot for your dog. Put simply, if it's too hot for you to hold it there for five seconds, it's too hot for them.

During a heatwave, make sure your pet has access to water and shade at all times. It's generally recommended to keep them inside (or out of the heat) between 11am and 3pm, which is the hottest time of the day.

How to stay cool (and safe) during an Australian heatwave

If you do need to head outside, it pays to be prepared:

• Wear loose, light-coloured, breathable fabrics
• Apply (and reapply) SPF—UV levels remain extreme even in the shade
• Carry water and sip regularly, even if you don’t feel thirsty. Cool (not cold) water is generally recommended
• Avoid strenuous activity during the hottest parts of the day
• Seek air-conditioned spaces whenever possible. If you don't have air-conditioning at home, try a cinema, library, or shopping centre to escape the heat
• At home, close blinds during the day, use fans strategically, and opt for cool showers or damp cloths to lower body temperature.