What is it?
A windbreaker or windproof jacket keeps the wind out. Some of them will be able to keep you dry through very light showers but a windbreaker is most definitely not Waterproof. I See the post on Waterproof Jackets here.
Why is it compulsory?
When you’re exercising perspiration serves to cool you down. A wind or even a small breeze speeds up the cooling process and can result in your skin being colder than the ambient air temperature. Couple that with being still for an extended period of time and you can get hypothermia, a life threatening condition result in death and unconsciousness. Having a windproof jacket allows us to keep the wind off our skin and prevent the rapid cooling.
Do I need Windproof and Waterproof?
The short answer is no. A waterproof jacket is also a windproof jacket so you don’t need a separate windproof jacket. It is however worth having both as the windproof is far lighter and smaller than the waterproof and many race organisers will allow you to use a windproof jacket if there is definitely no chance of rain. The weight and packing space requirements can be quite significant between the windproof and waterproof. Always have both if you can afford it but if your budget is tight then get the best possible waterproof jacket first. You can always buy a windproof jacket later.
Why would I want one?
Windproof jackets alone will not keep you warm but they are fantastic for beating the early morning chill or keep a light drizzle from messing up your run. They are often very lightweight and pack down to the size of a small orange meaning they will fit anywhere. Keep one with you anytime you’re running – they even work as an effective sun screen if you’ve forgotten to bring along the sunblock. Using a long sleeve fleece underneath a windbreaker can keep you warm even in temperatures approaching zero, especially if you are moving and generating body heat.
As with any trail racing jacket consider what other equipment you will be wearing. Take into account any layers you might want to wear underneath the jacket. Also take into account how your chosen pack will fit with the jacket and all the layers. Try to keep the fit snug and close to the body. You don’t want the jacket flapping about, making a noise and throwing you off-balance in the wind.
Features to look
Lightweight ( 50 g – 100 g).
Small pack size (size of an orange or smaller).
Water resistant (useful in light showers).
Breathable (allows sweat to escape through material and possible armpit zips).
Bright in color (easy to see in a rescue scenario).
Light reflecting properties(good for running at night and early morning in urban environments).