Scotland might not be world-famous for its weather, but the high humidity and cool year-round conditions are good news for whisky lovers. Thanks to its special climate, Scotland has a reputation for producing some of the world’s finest whiskies ranging from the big names like Macallan, Glenfiddich and Laphroaig to smaller boutique operations like Edradour and Bladnoch.
While Scotland sits geographically quite far to the north, it enjoys a mild, cool and rainy climate thanks to the Gulf Stream and prevailing south-westerly winds which bring in moisture from the nearby Atlantic. In fact, the Highlands are one of Europe’s wettest regions with up to 4577mm of rain every year.
This ample rainfall has two key benefits when it comes to making world-class whisky. Firstly, it ensures the Scotland has an abundance of pure fresh water which is one of the key raw ingredients in making whisky. Water is so important to the taste of Scotch that distilleries usually own a water source to ensure a constant supply of crystal clear water which is free from any potential contamination.
The second reason why all that rain is so useful relates to how Scotch whisky matures. As the spirit ages in the cask small quantities of liquid soaks through the wood, evaporates and is lost. This is the so-called “angel’s share”. The amount of liquid and the proportion of alcohol that evaporates varies depending on the climate. Scotland’s cool and humid climate helps to reduce the overall amount of liquid lost, but at the same time a higher proportion of alcohol than water tends to be lost. This has the effect of softening the whisky’s flavour profile over the years as the alcohol content (ABV) is reduced.
In contrast, in hotter and drier places such as Kentucky in the U.S.A. more liquid tends to be lost and a higher proportion of water evaporates. This means that the alcohol content of the cask increases over time which in turn has an impact on the overall flavor profile.
The damp Scottish climate thus plays a critical role in the taste of the Scotch in your glass, and it also affects how much whisky is lost each year to evaporation in the cask. This is crucial since if the alcohol content drops below 40% ABV the spirit can no longer be legally called whisky. Typically in Scotland a cask might lose 1-2% of spirit per year, while in hotter climates this can be as high as 10%. This is why it is very important for distilleries to monitor the levels in each casks through a process known as “regauging”.
Although there are many more factors which determine the flavour profile of Scotch such as the cask type, use of peat, and the distillation process, Scotland’s cool and humid climate has enabled the country to produce world-leading whiskies for generations. The mellow, effortlessly smooth character of fine Scotch cannot be replicated anywhere in the world, making it a magnet for collectors and investors across the globe.