As we all know when it comes to any type of fishing much depends on the weather. Salmon can be notoriously difficult to catch and are very unpredictable. Being lucky enough to have decent weather conditions can often be the difference between a difficult week and an excellent week in terms of catches. As salmon anglers, we have to hope that mother nature is feeling in a kind mood.
During the autumn months, the weather can be quite variable in Scotland. Often it can be warm, and the month of September can feel like an extension of summer. This can result in river levels being low and the water temperatures high. This is hardly ideal for salmon fishing. During the autumn months, you want the weather to turn colder and wetter. Nothing beats a good spate in early September to freshen conditions and clean out the river after a long hot summer like we have had in Scotland this year. If this is then coupled with a drop in temperature and some night time frosts you have all the ingredients for good salmon fishing.
Believe it or not for this to materialise the weather as far afield as Africa can have a bearing on how much rain we get in Scotland. During September and October heat builds on the safari plains of Eastern Africa and this causes large rain clouds to form. These clouds merge together to produce areas of low pressure which can become tropical storms which travel east over the Pacific towards the Caribbean. During this process, the storms can intensify and transform into hurricanes as they gain energy from the warm seas. The hurricanes can either make landfall in the Caribbean or travel northwards along the eastern seaboard of Central and then North America. Often the storms lose their intensity and with it their hurricane status. These storms are still thousands of miles away from Scotland, but they can then encounter what is known as the jet stream.
The jet stream is a very fast moving ribbon of air which runs high up in the upper atmosphere. It runs around the world from east to west. To the north of the jet stream it is colder and to the south it is warmer with more tropical air prevailing. The bigger the temperature gradient on the north and south of jetstream the stronger it gets.
The jet stream can pick up the remanence of these hurricanes and move them westwards across the Atlantic at great speed towards the UK. Depending on the exact position of the jetstream these ex-hurricanes can bring large amounts of wind and rain to Scotland and subsequently a lift in river levels.
So if you are salmon fishing in Scotland in the next few weeks, keep your fingers crossed that there are plenty of rain clouds brewing over the hot dusty plains of Eastern Africa as this could be the difference between success and failure!