Learn Hardcore German: Ist dir auch kalt, oder ist dir warm?

If you say Ich bin kalt, this sounds like you are a cold person in character (emotionally cold, unapproachable), or even “frigid” in a sexual sense. So:

Ist dir kalt? – natural, standard way to ask if you feel cold.
Bist du kalt? – wrong for physical temperature, and suggests something very different.

Why is dir in the dative case here?

Dir is the dative form of du (you, singular informal). The structure jemandem ist kalt/warm uses the dative of the experiencer:

Mir ist kalt. – It is cold to me.
Dir ist kalt. – It is cold to you.
Ihm ist kalt. – It is cold to him.

German treats the person who experiences the feeling as an indirect “recipient” of the state, so they go into dative. This is similar to other impersonal constructions:

Mir ist langweilig. – I’m bored.
Uns ist schlecht. – We feel sick.

So dir is dative because the pattern is jemandem ist + Adjektiv.

Who or what is the subject in Ist dir kalt? There is no es.

Grammatically, kalt is a predicate adjective, and there is an implicit dummy subject es (it), which is often omitted in such short questions:

Ist dir (es) kalt? – (Is it) cold to you?

In full sentences you can use es:

Es ist mir kalt. – Completely correct.
In everyday speech, many people shorten it to Mir ist kalt.

In questions, especially short ones, the es is almost always dropped:

Ist dir kalt? (far more common than Ist es dir kalt?, but both are grammatically fine)

What exactly does auch mean in Ist dir auch kalt?

Auch means also / too / as well. In this sentence, it implies a comparison with someone or something already mentioned:

Mir ist kalt. Ist dir auch kalt?
– I’m cold. Are you cold too?

So auch indicates that the speaker assumes someone else (the speaker, other people, or maybe everyone in the room) is cold, and is asking whether the listener shares that state.

Without auch, it’s a neutral question:

Ist dir kalt? – Are you cold? (no implication about others)

Why is auch before kalt and not at the end, like Ist dir kalt auch?

German particles and adverbs like auch normally appear in the middle field, before the main verb at the end (if there is one) and usually before predicate adjectives:

Ich bin auch müde. – not Ich bin müde auch.
Mir ist auch kalt. – not Mir ist kalt auch.

So Ist dir auch kalt? is the neutral, natural word order.

Ist dir kalt auch? sounds unnatural or strongly non‑standard in most contexts. You might see final auch in regional dialects, but in standard German, place auch before the adjective kalt.

Could I say Ist es dir auch kalt? instead of Ist dir auch kalt?

Yes, you can. Both are grammatically correct:

Ist dir auch kalt? – very common and perfectly natural.
Ist es dir auch kalt? – also correct, slightly more explicit or careful.

In everyday conversation, especially in short questions, Germans often drop the dummy es:

(Es) ist mir kalt. → Spoken: Mir ist kalt.
Ist (es) dir kalt? → Very often: Ist dir kalt?

So Ist dir auch kalt? is the more typical spoken form.

Why is it ist dir warm and not bist du warm?

Exactly the same reason as with kalt:

Mir ist warm. – Literally: To me is warm → I feel warm / I’m warm.
Dir ist warm. – You feel warm.

Using sein (ist) with a dative experiencer is the normal way to talk about how warm or cold someone feels.

Bist du warm? is not used for body temperature. Historically, warm could be slang for “homosexual”, so Bist du warm? can sound like “Are you gay?” (now outdated and potentially offensive). For temperature, always use:

Ist dir warm? / Ist Ihnen warm?
Mir ist warm. etc.

Why is oder used here? Is this the same oder as in German tag questions like …, oder?

In Ist dir auch kalt, oder ist dir warm?, oder is the normal or conjunction, just like English or:

Ist dir auch kalt, oder ist dir warm?
– Are you cold too, or are you warm?

So it offers a choice between two possibilities.

There is another common use of oder as a kind of tag question:

Dir ist kalt, oder? – You’re cold, right?

Here, oder does not connect two alternatives; it works more like right? / isn’t it? The meaning is different and the intonation is different.

In your sentence, oder is the normal “or.”

Is the comma before oder obligatory in Ist dir auch kalt, oder ist dir warm?

You are connecting two main clauses:

Ist dir auch kalt
ist dir warm

German rules allow a comma, but do not strictly require it, when two main clauses are connected by oder (or und) and the clauses are short and closely related.

So both are acceptable:

Ist dir auch kalt, oder ist dir warm? – with comma (more formal/clear).
Ist dir auch kalt oder ist dir warm? – without comma (also correct).

In careful writing, many people prefer the comma because it makes the structure clearer.

Could I shorten it to Ist dir kalt oder warm? without repeating ist dir?

Yes, that is very natural. German, like English, often ellipses repeated parts:

Ist dir (kalt) oder (ist dir) warm? → Ist dir kalt oder warm?
– Are you cold or (are you) warm?

Because ist dir clearly applies to both adjectives, you don’t need to repeat it. Your original sentence with full repetition is also correct, just slightly more explicit:

Ist dir auch kalt, oder ist dir warm?

Should I say warm or heiß for “hot” when talking about how a person feels?

For body temperature / how you feel, warm is usually enough and more common:

Mir ist warm. – I’m warm / I feel warm.
Mir ist sehr warm. – I’m very warm / I feel very warm.

You can use heiß if you are extremely hot, almost overheated:

Mir ist heiß. – I’m (really) hot.
Ist dir heiß? – Are you (very) hot?

So:

Mild to strong warmth: warm
Very strong heat, sweating: often heiß

In contrast, English “I’m hot” is usually Mir ist warm or Mir ist heiß, depending on intensity, but Ich bin heiß sounds sexual (I’m horny), not temperature-related.

What is the difference in meaning between Ist dir kalt? and Dir ist kalt?

The word order signals question vs statement:

Ist dir kalt? – Yes/no question: Are you cold?
– Verb (ist) in first position → question.
Dir ist kalt. – Statement: You are cold.
– The verb (ist) in second position → declarative sentence.

So if you keep exactly the same words but change the order, you go from a question to a statement, just like:

Bist du müde? (question) vs Du bist müde. (statement).

How would this sentence change in the polite/formal “you” form?

Dir is the dative of informal du. For formal Sie, the dative form is Ihnen.

So:

Informal: Ist dir auch kalt, oder ist dir warm?
Formal: Ist Ihnen auch kalt, oder ist Ihnen warm?

Similarly:

Mir ist kalt. – I am cold.
Ihnen ist kalt. – You are cold (polite).

Is Hast du kalt? also correct, like in Swiss German?

In Swiss German, sentences like Ich habe kalt / Hast du kalt? are normal. However, in standard German (Hochdeutsch) used in Germany and most writing/teaching, this is considered dialectal / non‑standard.

Standard forms are:

Mir ist kalt. – not Ich habe kalt.
Ist dir kalt? – not Hast du kalt?

So if you are learning standard German, use jemandem ist kalt/warm, not jemand hat kalt/warm.