Too cold is the more common mistake
Most of the wine mistakes that happen to us at home are not about wine being too warm, but too cold. A bottle comes straight out of the fridge, feels ice-cold, and in that state almost any white wine tastes of very little: the aromas retreat and what is left is mostly acidity.
That is a particular shame with wines that actually have something to say. A Grüner Veltliner with fine spice or a Riesling with stony depth needs a little warmth just to show that in the first place. Letting the bottle sit out of the fridge for ten minutes is often the simplest improvement you can make to a wine evening.
Steinfeder and Federspiel: cool, not icy
Lighter wines such as a Steinfeder or a slender Federspiel handle cool temperatures well, because their freshness is exactly what defines them. Even so, they should not go into the glass ice-cold. If the bottle comes straight from the fridge, a few minutes on the table are usually enough for the scent and fruit to open up without the wine losing its tension.
A simple guide from our own experience: if the glass feels unpleasantly cold to the touch, the wine is usually too cold to smell properly. Once you catch the first scent without having to push your nose deep into the glass, the temperature is roughly right.
Smaragd needs time and a touch more warmth
A dense, ripe Smaragd benefits from being served a little warmer than the lighter styles. Served too cold, it often feels closed and one-dimensional, even though this is precisely the style that usually has the most layers to show: ripe fruit, spice, sometimes a stony, saline depth underneath.
With Smaragd, time is often just as important as temperature. Letting a glass sit for a quarter of an hour before really smelling it changes more with these wines than any number of degrees. If you open a special Smaragd, give it that time rather than judging it straight after pouring.
The glass makes more difference than you'd think
A narrow, tulip-shaped glass that curves inward at the rim concentrates scent towards the nose, while a wide, open glass lets it escape more easily. For Grüner Veltliner and Riesling, a classic, medium-sized white wine glass is usually entirely sufficient. More important than the exact shape is often that the glass is not filled to the top: only then is there room for the scent to actually gather inside it.
We do not see this as a rulebook. A good wine in a simple glass is still a good wine. But anyone who has tried the same Riesling from a large glass and a small one notices quickly that there really is a difference, and it is not imagined.
Our own rules of thumb when we open something at home
For us it usually goes like this: Steinfeder and light Federspiel wines come to the table cool and get to sit there for a few minutes. Fuller Federspiel wines and most Rieslings get a little more time so the aromas can show themselves. A Smaragd is poured first and properly tasted last, because it needs the most time to open up.
It is not a protocol, more a habit that grew out of a lot of opened bottles. If you are unsure, the rule of thumb rarely goes wrong: start a touch too warm and cool it down if needed, rather than talking a good wine out of showing itself by serving it cold from the start.