How to relate wind chill, temperature, and cycling I'm interested in how wind chill and temperature come into play while cycling.  If I rode on one day with the temperature at 15°F (-9°C), but the wind chill was 1F (-17°C), how would that relate to a day where the temperature is 10°F (-12°C) or 20°F (-6°C) with the same wind chill?
Ok, let's start with wind chill.  The faster the wind, the more chill Wind Chill chart from the National Weather Service Read along the top for the temperature without wind, then down for wind chill at different speeds.  So, for example, at 15 degrees Fahrenheit (-9°C) in a 15mph (6.7 m/s) wind, effective temperature is 0 degrees Fahrenheit (-18°C). (chilly!) That chart only works up to 40 degrees F (4°C), but it gives the idea! This Wind chill Calculator allows you to put in any value, and speed of air

Of course, that's if you're standing still.  If you're cycling you almost always have a headwind, Here is a link to a page with masses of detailed information about headwinds.  The faster you go, the faster the effective windspeed, and the lower the temperature felt.  This can be really helpful on a hot summer day, or really chilly in a cold winter!  

When cycling you have to take this into account - in the winter, layer up (and find a wind proof jacket if possible.)  In the summer, it means that you can actually go up that big hill without totally overheating! I remember one hot day, on a steep incline, I rounded a bend, and came straight into the lee (wind shielded) side of the hill - in seconds I was feeling way too hot, without the cooling breeze.