Very often cyclists and walkers set out wondering how the weather will turn out and if you are going to be able to go that extra few miles without “having to wring out your cap” as a friend of this blog, Brownhills Bob, would say. (I really like that expression).
What I going to explain to you below is a simple system called the cross winds rule. It is very simple to use and generally fairly accurate. A couple of words of warning when using it. Firstly be sure when you are testing the rule that you are not “feeling” deflected wind from a building, hill or mountain. If you are receiving deflected wind then you need to move to a clearer space where interference is less likely.
Secondly, if you are ever lucky enough to travel to the southern hemisphere the rule reverses.
Changes in the weather generally comes about when low pressure moves across a locality. surface winds (the winds we feel in our face and on our backs) move anticlockwise when the weather is going to get worse and clockwise when better weather is on its way.
So how to apply the rule.
1. Stand with your back directly into the wind. Look up at the clouds. If they are moving from your left side then the weather will normally deteriorate.
2. Stand with your back directly into the wind. Look up at the clouds. If they are moving from your right side then the weather will normally improve.
3. Stand with your back directly into the wind. Look up to the clouds. If the clouds are moving parallel to the lower wind then the weather is unlikely to change.
The forecast you get from the rule is generally good for a period of between two and six hours, however, there is nothing stopping you making more observations along the way.
Cross Winds Rule – Alan Watts Instant Weather Forecasting.