I usually keep some rum, some tequila and some vodka in the freezer to fix some drinks. Unfortunately, the freezer temperature is too cold for the best 18 years single malt whisky. Even the fridge keeps it a bit too cold. In fact, the temperature is always a personal preference, but it should be somewhere around 15°C or 59°F. Adding ice to your whisky (or other spirit) will not only drop the temperature too close to 0°C or 32°F but it will also dilute the content of your glass. To avoid taste buds from being numbed by the ice and the cold, adding whisky stones will help your drink in reaching the proper temperature. That's how I have my Scotch "on the rocks", avoiding it from being too cool or too cold.