Heat and humidity calculator: average level for your holiday

Our heat and humidity calculator is here to help you find the perfect holiday destination while avoiding any extreme heat and humidity that could create discomfort. Understanding how heat and humidity works is a complicated business, so read our guide to find out more about how we measure heat and humidity, as well as to see where in the world experiences crippling levels of heat and humidity at certain times of the year.

Heat & Humidity Calculator

Heat and humidity calculator: average level for your holiday

Air temperature on its own is not necessarily the best indicator of how hot the weather may feel in your chosen holiday destination. For example, the resort of Sharjah just 12 miles north of Dubai, can feel quite tolerable in April even though the air temperature is normally in the low thirties. At the same time, Pattaya in Thailand can feel unbearably hot when the temperature there is exactly the same as in Sharjah. The difference can be explained by the level of water vapour in the air - the humidity.

Our heat and humidity calculator shows how hot it feels © Pelfophoto - Dreamstime.com
Our heat and humidity calculator shows how hot it feels © Pelfophoto - Dreamstime.com

To help you find the right destination, we have created a heat and humidity calculator that takes the average air temperature and humidity to create a heat and humidity index (more about this below). This shows the level of discomfort that is likely to be encountered at each destination when a combination of high air temperatures and high levels of humidity can make it feel unbearably hot.

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Understanding the heat and humidity index

The system we use for our heat and humidity calculator, and for our climate guides, comes from a formula that was developed by researchers who put people to the test. They subjected volunteers to different levels of temperature and humidity, before asking them to describe how they felt.

An index was then created from these results, and this is the one we use. The index breaks heat and humidity down into five levels of intensity, from none to extreme, and the results we display for each destination are based on 30 years' worth of temperature and humidity data.

Icon Level Description
No heat & humidity None No discomfort; it does not feel too hot
Low heat & humidity Low Slight discomfort; some might feel the heat and humidity
Moderate heat & humidity Moderate Moderate discomfort; everyone will feel the heat and humidity
High heat & humidity High High sense of discomfort; everyone will feel the increased heat and humidity
Very high heat & humidity Very High Very high sense of discomfort; conditions feel very hot and close
Extreme heat & humidity Extreme Extreme sense of discomfort; conditions can feel unbearably hot

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About heat and humidity

We humans naturally regulate our body temperatures, so when we get too hot, we sweat. This perspiration then evaporates, which helps us to cool down. As air temperature rises, the difference between body temperature (roughly 37°C) and the air temperature narrows.

Remember to stay hydrated © Julija Sapic - Fotolia.com
Remember to stay hydrated © Julija Sapic - Fotolia.com

If you're in a fairly dry environment, such as the Sahara Desert, this is not a problem, as your sweat can still evaporate at low levels of humidity even if the temperature is high. As long as you keep replacing the water that evaporates off your skin by staying hydrated, you can maintain a normal body temperature in a desert when the air around you is at a higher temperature. However, in a less dry environment where humidity is higher, feelings of discomfort start to occur because the body's evaporation process works less efficiently in more humid conditions, which makes maintaining normal body temperature far more difficult.

Did you know?As air temperature rises, its capacity to hold water vapour increases. In fact, at 35°C the air can hold 75% more water vapour than it does at 25°C

One way of expressing the level of humidity in the air is to use the percentage figure that shows the actual amount of water vapour compared to the maximum possible at that temperature - this is known as relative humidity. Yes, for a given temperature, air can only contain a certain amount of water vapour; when the maximum is reached it condenses as dew or forms fog.

Sticking with Sharjah, in April it has an average maximum daytime temperature of 33°C and relative humidity of 35%, which according to the heat and humidity calculator produces a moderate level of discomfort. At the same time the average maximum daytime temperature in Pattaya is also 33°C but the relative humidity is usually between 55% and 60%, which the heat and humidity calculator shows will produce an extreme level of discomfort.

Below 24°C most people can cope with all levels of relative humidity that they are likely to come across without feeling uncomfortably hot. This is because there is sufficient difference between 24°C and normal body temperature for the body not to become overheated.

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Heat and humidity: where and when?

Heat and humidity will always be at its peak in the summer months of the destination you're in, which could be anything from April to September in the northern hemisphere, and November to February in the southern hemisphere.

In winter most of the Caribbean has only moderate heat and humidity © Sébastien Closs - Fotolia.com
In winter most of the Caribbean has only moderate heat and humidity © Sébastien Closs - Fotolia.com

There are fewer destinations in the southern hemisphere that experience extreme levels of heat and humidity, really only certain parts of Australia. This is because in South America, for example, there are high mountains in the west, and in the east you are never far from the cool South Atlantic. It's a similar story in southern Africa, which has a cold ocean to the south and high elevations inland. As a rough guide, you will find that the following destinations endure extreme levels of heat and humidity at these times of year:

Month Destination(s)
January Parts of Australia (Western Australia; Northern Territory)
February Parts of Australia (Western Australia; Northern Territory), north eastern Kenya
March North eastern Kenya
April Thailand, Cambodia, Burma, parts of India,
May Thailand, Cambodia, Burma, parts of India, parts of Oman
June Dubai, Persian Gulf, Oman, parts of India
July Dubai, Persian Gulf, Oman, Upper Egypt, parts of India, USA (southern Arizona; southwest California)
August Dubai, Persian Gulf, Oman, Upper Egypt, USA (southern Arizona; southwest California)
September Dubai, Persian Gulf, Oman
October Oman, parts of Australia (Northern Territory)
November Parts of Australia (Western Australia; Northern Territory)
December Parts of Australia (Western Australia; Northern Territory)

How heat and humidity affects you will, of course, be different to the next person however, it is vital that you know roughly what to expect for your next holiday to avoid any disappointment, let alone discomfort. Our heat and humidity calculator is designed to guide you in the right direction for what is acceptable to you, and hopefully you also have clear understanding of how we have measured and reported on heat and humidity around the world, throughout the year.

If our heat and humidity calculator alone isn't enough to help you decide on your ideal holiday destination, then check out the other guides in our detailed holiday weather series including how to plan for tropical storms, where to find warm sea temperatures and tips for avoiding UV damage, among others. If you have a specific destination in mind, head over to the climate guide section to see the annual weather averages as well as the upcoming five-day forecast. You can also get booking via the travel and discounts section, with the latest offers from airlines and holiday companies.

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More holiday weather parameters:

Heat & Humidity by month

Below is the Heat & Humidity levels for popular holiday destinations around the world by month. Select a destination to see more holiday weather parameters.

Heat & Humidity in January

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Heat & Humidity in February

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Heat & Humidity in March

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Heat & Humidity in April

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Heat & Humidity in May

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Heat & Humidity in June

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Heat & Humidity in July

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Heat & Humidity in August

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Heat & Humidity in September

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Heat & Humidity in October

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Heat & Humidity in November

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Heat & Humidity in December

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