How to determine wind chill when riding a motorcycle?

When riding a motorcycle, the temperature you feel is not the actual outside ambient temperature: it is much lower because of your speed. This is what we call the wind chill, or wind chill factor, that is the temperature you actually feel when riding. Although it is not easy to determine with much accuracy, there is a way to calculate it approximately.

What is wind chill exactly?

Wind chill, also called wind chill factor, is the temperature perceive by your body when riding your motorbike. It is always lower than the actual ambient temperature because the flow of air on your body will make you feel colder than is it when you are static.

Wind chill doesn’t mean that the air is getting cooler, but your perception of it will be because of your body reactions. Several factors can influence your perception of the cold, such as rain or air moisture.

Although wind chill is very difficult to determine with accuracy, as it is based on human perceptions, it is actually very real and dangerous.

How to calculate wind chill?

The fact that wind chill is based on human perceptions and several nebulous factors make it very difficult to calculate with accuracy. There is actually no exact way of measuring wind chill, but many attempts have been made to calculate the effect of cold on our bodies as it is affected by the wind, in order to reduce risks.

Still, no worldwide standards have been set. For instance, Europe and North America (U.S. and Canada) have their own standard way of measuring wind chill, but in fact, each weather bureau in each country use their own formula.

European wind chill index

The European wind chill index, for instance, measures it according to the ambient temperature and your riding speed. The chart looks like this:

Speed	Wind chill
0 km/h	10°C	5°C	0°C	-5°C	-10°C	-15°C
10 km/h	8,6°C	2,7°C	-3,3°C	-9,3°C	-15,3°C	-21,2°C
30 km/h	6,6°C	0,1°C	-6,5°C	-13°C	-19,5°C	-26°C
50 km/h	5,5°C	-1,3°C	-8,1°C	-15°C	-21,8°C	-28,6°C
90 km/h	4,1°C	-3,1°C	-10,2°C	-17,4°C	-24,6°C	-31,8°C
110 km/h	3,6°C	-3,7°C	-11°C	-18,3°C	-25,6°C	-32,9°C
130 km/h	3,2°C	-4,2°C	-11,7°C	-19,1°C	-26,5°C	-33,9°C

North American wind chill equation

On the other hand, the North American index, provided by the National Weather Service, takes in account the ambient temperature (T) and the wind speed (V) rather than your riding speed. It is calculated according to this equation:

Wind Chill (°F) = 35,74 + 0,6215T – 35,75(V^0,16) + 0,4275T(V^0,16)

Here is an extract from the National Weather Service wind chill table:

Wind speed	Wind chill
0 m/h	40°F	30°F	20°F	10°F	0°F	-10°F
10 m/h	34°F	21°F	9°F	-4°F	-16°F	-28°F
20 m/h	30°F	17°F	4°F	-9°F	-22°F	-35°F
30 m/h	28°F	15°F	1°F	-12°F	-26°F	-39°F
40 km/h	27°F	13°F	-1°F	-15°F	-29°F	-43°F
50 km/h	26°F	12°F	-3°F	-17°F	-31°F	-45°F
60 km/h	25°F	10°F	-4°F	-19°F	-33°F	-48°F

What risks does wind chill involves?

As we already said, although the wind chill factor is a bit of a moving target because it is based on human perception and several variable factors, its effects are very real and can be dangerous to your physical health. The two main risks are frostbites and hypothermia.

Frostbites

Frostbites are a deterioration of your body tissues resulting of being exposed to severe cold: the moisture in the tissues crystallize and turn into ice, leading to frostbites. Although it might seem trivial, if you are affected, you should get medical help as soon as possible as it can lead to severe complications, like infection and, in the worst case, amputation.

Note that frostbites can appear very quickly. Depending on the wind speed, they can appear less than half an hour from a wind chill of -30°C (-20°F), and less than five minutes from a wind chill of -45°C (-49°F). The fastest the wind goes, the quicker you might get frostbites.

Hypothermia

Hypothermia occurs when the extremities of your body are very cold and your overall body temperatures falls under 35°C (95°F). Although hypothermia won’t kill you, it may lead to severe lasting problems, such as kidneys, pancreas or liver complications.

How to deal with wind chill when motorbiking?

One might think ‘Alright, I’m just gonna move where it is warm and avoid wind chill !’. Well, no. Unfortunately, that won’t be enough as you might not be aware of weather conditions in the targeted areas. As some regions are known to be quite warm, they may still be subject to low temperatures without you knowing it. For this reason, do not think ‘How to avoid it’ but rather ‘How to deal with it’.

Plan your trip as well as possible

The best advice we can give you is to plan your trip as well as possible. Plan your route and check weather conditions for each part of it. Note that usual temperature forecast are based on static conditions and do not take sun, moisture or wind factors into account. You can try to check for farming weather forecast, as they are usually more accurate and give more information about wind speed.

Also, remember to check the elevation and if the area is subject to snow weather and freezy temperatures. For the record, freezy temperatures are below 0°C (32°F).

Get proper gear

The second obvious piece of advice is to get proper gear. Always remember to dress in layers so you can adapt to various temperatures without having to change all your gear. Here is our recommendations:

• Have at least three pairs of gloves at any time: a thin underneath pair of glove, that heats well and dries well in case of rain, along with two pairs of quality motorcycling gloves (one you use and a spare pair in case of rain).
• Have a balaclava to hand at any time.
• Use a full face helmet.
• For your upper body, wear three to five layers: a thin, breathable long sleeve shirt, a sweatshirt of thicker long shirt or sip-up wool vest, a leather jacket and a quality motorcycling jacket. We recommand to get a motorcycling jacket that comes with an inner and an outer shell. These are the best quality.
• For your legs, have three layers to hand: a pair of long johns, a pair of quality motorcycling trousers and a pain of rain trousers. The latter actually stops the wind and holds the heat quite well.
• Finally, always have at least two or three pairs of woollen socks to hand. You might have to wear to pairs at a time when the wind chill is very low, and you definitely want some spare ones in case of rain.

Of course, in case of low temperatures, also remember to adapt your driving and change for winter tyres if necessary.