Learn Hardcore German: Ich zittere, wenn mir sehr kalt ist.

German uses the dative case (mir) in certain expressions of physical state or feeling, where English would just use me/I without thinking about case.

mir = dative of ich (to me / for me)
mich = accusative of ich (me, as a direct object)

The pattern mir ist kalt literally means:

“To me, it is cold.”

So mir is the person experiencing the cold, not being acted on like a direct object. That’s why German uses the dative, not the accusative.

If you said mich ist kalt, it would be clearly wrong to a native speaker—ist never takes mich like that.

Why is it mir ist kalt and not ich bin kalt?

mir ist kalt and ich bin kalt do not mean the same thing.

mir ist kalt = I feel cold / I am cold (temperature)
- literally: “To me, it is cold.”
- This is how you normally say you are cold in German.
ich bin kalt = I have a cold personality / I am frigid / emotionally cold
- This talks about character or emotional warmth, not your body temperature.

So in the sentence, wenn mir sehr kalt ist means when I feel very cold, which is why mir (dative) and ist (it is) are used, not ich bin.

Why does the verb ist come at the end of wenn mir sehr kalt ist?

Because wenn introduces a subordinate clause in German, and in subordinate clauses the finite verb goes to the end.

Word order pattern:

Main clause: Subject – Verb – (other stuff)
- Ich zittere. – I shiver.
Subordinate clause with wenn: wenn – (subject / objects etc.) – verb at the end
- wenn mir sehr kalt ist – when I am very cold

So:

Ich zittere, wenn mir sehr kalt ist.
- Main clause: Ich zittere (verb in 2nd position)
- Subordinate clause: wenn … ist (verb at the end)

Why is there a comma before wenn?

In German, subordinate clauses are always separated from the main clause by a comma.

Ich zittere, ← main clause
wenn mir sehr kalt ist. ← subordinate wenn-clause

This is a fixed punctuation rule in standard written German:

Main clause + subordinating conjunction (like wenn, weil, dass, etc.) → comma before the conjunction.

Can I put the wenn-clause first? How would the sentence look then?

Yes. You can put the wenn-clause first to emphasize the condition. The word order will change slightly in the main clause:

Wenn mir sehr kalt ist, zittere ich.

Rules:

In German, whatever comes first in a sentence takes the “Vorfeld” (the first position).
The finite verb of the main clause must still be in second position of that clause.

So:

Clause 1 (subordinate): Wenn mir sehr kalt ist, … (verb at the end)
Clause 2 (main): zittere ich. (verb in 2nd position)

Why is it sehr kalt and not sehr kalte?

Here, kalt is used as a predicative adjective, linked with ist (to be). In German:

Predicative adjectives (after sein, werden, bleiben) do not take any endings.
- Es ist kalt. – It is cold.
- Mir ist sehr kalt. – I am very cold.

You only see endings like -e, -en, -er, -es when the adjective comes before a noun (attributive use):

die kalte Luft – the cold air
ein sehr kalter Tag – a very cold day

Since kalt here doesn’t describe a noun directly but is part of ist kalt, it stays in the base form kalt, even with sehr in front of it: sehr kalt.

Could I say Ich zittere, wenn ich sehr kalt bin instead?

Grammatically, ich bin is fine German, but in this context ich bin sehr kalt sounds wrong or at least very odd.

Reasons:

ich bin kalt usually means “I am (emotionally) cold / distant / frigid”.
To talk about feeling cold (temperature), German uses the “mir ist kalt” pattern.

So native speakers would normally not say:

✗ Ich zittere, wenn ich sehr kalt bin.

They would say one of:

Ich zittere, wenn mir sehr kalt ist.
Ich zittere, wenn mir kalt ist. (without sehr)
Or just: Ich zittere, wenn mir kalt ist.

Could I also say Ich zittere, wenn es mir sehr kalt ist?

You will hear:

Es ist mir kalt.
Es ist mir sehr kalt.

So in principle, the structure es … mir … kalt does exist. But in a wenn-clause, the version without es sounds more natural:

Ich zittere, wenn mir (sehr) kalt ist. ← most natural
Ich zittere, wenn es mir (sehr) kalt ist. ← possible, but feels heavier / less idiomatic in this exact sentence

Native speakers overwhelmingly prefer wenn mir kalt ist here. If you use es, you usually keep the English-like order:

Es ist mir kalt, wenn ich lange draußen bin.
(It is cold to me / I’m cold when I’m outside a long time.)

What exactly does zittern mean? Is it the same as frieren?

They are related but not the same:

zittern
- basic meaning: to tremble, to shake, to shiver
- can be because of cold, fear, excitement, weakness, etc.
- Ich zittere. – I’m shaking / shivering.
frieren
- basic meaning: to be cold, to feel cold, to freeze
- specifically about feeling cold (temperature)
- Ich friere. – I’m (feeling) cold / I am freezing.

So:

Ich friere, wenn mir sehr kalt ist. – I feel very cold then.
Ich zittere, wenn mir sehr kalt ist. – I shiver when I’m very cold.

You can also say:

Vor Kälte zittere ich. – I’m shivering from the cold.

Why is the tense present here? Could I use a different tense with wenn?

German often uses the present tense to talk about:

general truths
repeated actions / habits

So Ich zittere, wenn mir sehr kalt ist describes a general rule: whenever this condition happens, this is what I do.

You can use other tenses with wenn, depending on the time reference:

Ich zitterte, wenn mir sehr kalt war.
- I used to shiver when I was very cold. (past habit)
Ich werde zittern, wenn mir sehr kalt ist.
- I will shiver when I am very cold. (future consequence; note that in German you can still often keep the present in the wenn-clause.)

But in the general, timeless sense (like in your example), the present–present combination is standard.

What is the difference between wenn and wann? Why is wenn used here?

wenn and wann both translate to when, but they are used in different situations:

wenn
- for repeated or conditional situations
- whenever / if
- Ich zittere, wenn mir sehr kalt ist.
  - Whenever / If I am very cold, I shiver.
wann
- for a specific point in time, usually in questions (direct or indirect)
- Wann kommst du? – When are you coming?
- Ich weiß nicht, wann er kommt. – I don’t know when he is coming.

Your sentence talks about what you do whenever a certain condition is true, so wenn is correct. Saying ✗ Ich zittere, wann mir sehr kalt ist is wrong.

Is mir kalt some kind of fixed expression I should memorize?

Yes. Mir ist kalt (or just Mir ist kalt) is a very common and useful fixed pattern:

Mir ist kalt. – I’m cold.
Mir ist warm. – I’m warm.
Mir ist heiß. – I’m hot.
Mir ist langweilig. – I’m bored.
Mir ist schlecht. – I feel sick.

In all these, mir is dative and marks the experiencer, and the adjective expresses the state you’re experiencing. So it’s a good idea to treat Mir ist kalt and similar expressions as a pattern and get used to using mir there.

Could I say Ich zittere sehr, wenn mir kalt ist instead? Does the meaning change?

Yes, you can say:

Ich zittere sehr, wenn mir kalt ist.

The meaning is slightly different in focus:

Ich zittere, wenn mir sehr kalt ist.
- Emphasis: how cold you are (very cold).
- I shiver when I am very cold.
Ich zittere sehr, wenn mir kalt ist.
- Emphasis: how strongly you shiver (a lot).
- I shiver a lot when I’m cold.

Both are correct; they just emphasize different parts of the situation.