Any bike rider knows that when planning a trip, many factors are to be taken in account, and this includes what we call the wind chill factor. The wind chill factor is the temperature you will feel when riding your motorcycle, being much lower than the actual outside temperature because of your speed. Wind chill is not easy to determine with accuracy, but still, it can be calculated with approximation, which comes in handy when planning a trip to colder destinations.
Definition of wind chill factor
Tounderstand how to determine wind chill factor, we must first understand the difference between heat and temperature. Temperature is an exact measure, that can be determined with instruments, as heat is a sensation that is relative to your environment. For instance, if you have been in a room at 70°F (temperature) for an hour, you will feel these 70°F quite precisely. Whereas if you enter a room at 70°F after spending an hour in a room at 50°F, the temperature you will feel will seem higher than 70°F (heat).
Understanding this, the speed at which you ride your motorcycle will also have an effect on the temperature you will feel while riding, which will always be lower than the actual outside temperature. This is what we call wind chill, or wind chill factor. It does not actually make the air colder, but just your perception of it. Other factors such as rain or air moisture can also influence your perception of the cold.
How to calculate wind chill factor?
As we explain, wind chill factor is based on human perception, and that is why it is so difficult to calculate with accuracy the effect of cold on a body affected by the wind. In fact, although many attempts have been made to determine wind chill, there is no exact measurement of it, nor any worldwide standards. Even though the US and Europe each have their own standards, the reality is that each country’s weather bureau use their own calculations.
This is why, when planning your trip, you should always take into account your personal context in order to plan the right equipment. Chilly people will always have to plan a higher wind chill, while people more resistant to the cold can plan lighter equipment accordingly.
North American (US & Canada) wind chill index
The North American equation for the wind chill index takes into account the outside temperature (T) along with the wind speed (V), according to the following formula:
Wind Chill (°F) = 35,74 + 0,6215T – 35,75(V0,16) + 0,4275T(V0,16)
You can get a wind chill table from the US National Weather Service. Here is an extract:
| 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 |
European wind chill factor equation
On the other hand, the European equation of the wind chill index also takes into account the ambient temperature, but rather your riding speed than the wind speed. Here is an extract from the European wind chill chart:
| 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 |
What risks are induced by wind chill?
Although wind chill factor cannot be determined with accuracy, it does not mean that it must not be considered seriously, as its consequences are real and can be very dangerous to your physical health.
Frostbites can lead to amputation
Many would think that frostbites are not that serious, but severe frostbites not taken care of may lead to infection and, in the worst possible case, amputation. Frostbites are a result of body tissues’ deterioration when exposed to severe cold: the tissues’ moisture freezes, often leading to a cracking of the skin.
Although we usually experience frostbites only in winter, you can see in the above charts that wind chill can bring you down to negative temperature very quickly. For this reason, be aware that frostbites can appear as soon as half an hour after your departure for a wind chill of -20°F (-30°C), and in less than 5 minutes for a wind chill of -49°F (-45°C).
Hypothermia can damage your organs
Hypothermia is defined by your overall body temperature falling under 95°F (35°C). This usually happens when your body’s extremities are getting too cold (hands, feet, head…), and that is why you should always make sure to protect them at best.
Hypothermia won’t kill you, but be aware that it may lead to severe complications due to a deterioration of your organs such as kidneys, pancreas or liver.