Alright, let’s confront the sake slurping elephant in the room.
Whenever the topic of sake comes up the first discussion is usually whether to drink it hot or chilled. And I’m here to tell you that like many things sake (and Japanese for that matter) there is no clear-cut answer. What I can tell you though, is both have their place.

Most people have probably had their introduction to sake through hot or warmed sake (incidentally called O-kan in Japanese). Then, at some point you may have met someone who proclaimed that no longer is it necessary to drink sake warm, it should be drunk chilled. Why? Because sake of days gone by was of a lesser quality and a bit rough, warming it up covered those flaws making the sake more palatable. Now, this is partly true. No doubt the sake making techniques in the old days were not as refined and calculated as they are today. Sake of old was not as aromatic and would’ve been gritty and nutty. The lack of refining techniques probably left some musty type flavours that magically disappeared when the sake was heated. Also, early sake was stored in cedar barrels which would also have contributed to a duller flavour profile. While these may be contributors, it’s not the only reason for warming sake. One glaringly obvious fact is that refrigeration as we know it didn’t exist until the last 150 odd years. Use of ice and snow for refrigeration did exist in some cultures but it was used mostly as a means of preservation of foods. In years gone by, food and drink was taken warm. One reason being it was considered healthier. So, to say sake used to be drunk warm to cover up flaws isn’t entirely correct. Chilled sake was occasionally drunk but warm was considered the standard.

 Now, in the case of modern sake, the ginjo style (refined, elegant and aromatic) has only really been around commercially for the last forty years or so. And in fact most of sake’s major technical breakthroughs have occurred in the last 100 years. The development of better rice milling machines for example, enabled brewers to start accurately milling to levels never done before. Along with other factors such as the development of new aromatic yeast strains and cultivating new hybrids of sake rice, this lead to a trend of lighter, aromatic more complex styles of sake that are better appreciated slightly chilled like a white wine.

However, keep in mind there are still breweries out there making sturdy old school sake. Sure, they are making it better than it would have been made a few hundred years ago but it’s still old school. I often find that some of those ricey, chewy junmai (pure rice) sakes can lack in the aroma department when chilled and tend to be a little dull. But give em’ a bit of heat and they can come alive. Notice I say a bit of heat. You don’t want to be serving sake at scalding temperatures. Just warmed, around 40 degrees is nice.

Another thing to take into account is climate. Here in Queensland I don’t often feel the hankering for warm beverages. However, those in cooler areas may find a slightly warmed sake on a cool evening to be quite lush. Japan’s winters can be brutal so it’s little wonder that the tradition of warm sake has held on.
So, it’s probably fair to say when it comes to nama sake (unpasteurized sake that is lively, fresh and zippy), ginjo and definitely daiginjo sake, chilled is the way to go. Honjozo and junmai are also likely to be good chilled but may work warmed depending on the sake. It can simply be a matter of trial and error. The good news is that many breweries put a little guide on the back label of their sake with serving temperature suggestions. As for the cheap nasty stuff? Heat it up.
Ordering in restaurants can be tricky. Sadly, I find a lot of staff (in Australian Japanese restaurants) don’t know their product and will happily offer to serve sake warm or chilled regardless of the sake. If they are strongly recommending you drink their sake warmed it’s sometimes because they know it’s nasty and heating will cover it up. Don’t be afraid to ask your server why they recommend heating. If you’re unsure, usually it’s safer to order the sake chilled and then if it isn’t happening for you ask them to warm it up.