Learn Hardcore Croatian: Zimi ne želim skinuti kaput u parku. - In winter I don’t want to take off my coat in the park.

Grammatically, it comes from the noun zima (winter) in the locative case, but in this form it has become a fixed adverbial expression meaning “during winter / in winter (in general).”

You normally don’t say u zimi for this general meaning. Instead, you use:

zimi = in winter (as a season, generally)
ljeti = in summer
u proljeće = in spring
u jesen = in autumn

If you said u zimi, it would sound unusual or at least marked, and would usually need something like an adjective:

u ovoj zimi – in this (particular) winter
Even then, speakers usually prefer ove zime instead.

Why is there no word for I in the sentence? Where is the subject?

Croatian is a pro‑drop language: the subject pronoun is usually omitted because the verb ending already shows the person.

želim = I want
želiš = you (sg) want
želi = he/she/it wants

So ne želim by itself already clearly means I don’t want. You only add ja for emphasis or contrast:

Ja zimi ne želim skinuti kaput u parku.
= I don’t want to take my coat off in the park in winter (implying others might want to).

In neutral sentences, leaving out ja is more natural.

What case is kaput in, and why does it look like the basic form?

Kaput here is in the accusative singular, because it is the direct object of the verb skinuti (to take off).

For masculine inanimate nouns like kaput, the nominative (dictionary form) and accusative singular look the same:

Nominative: kaput – a coat (subject)
- Kaput je nov. – The coat is new.
Accusative: kaput – coat (object)
- Skinem kaput. – I take off (the) coat.

So even though it looks like the base form, its function in the sentence is accusative object: something you are taking off.

Why is it u parku and not u park?

The difference is between location and direction:

u parku – in the park (where? – location) → locative case
u park – into the park (where to? – direction) → accusative case

In your sentence, the meaning is “in the park” (a place where the action happens), so Croatian uses u + locative:

u parku – in the park

If you were describing movement into the park, you would say:

Idem u park. – I’m going to the park. (direction → accusative)

Why does parku end with -u? What case is that?

Park is a masculine noun. Its key singular forms are:

Nominative: park (subject)
Genitive: parka
Dative/Locative: parku
Accusative: park

After the preposition u meaning in (location), Croatian uses the locative case. The locative singular of park is parku, so we get:

u parku – in the park (locative)

Compare:

Park je velik. – The park is big. (nominative)
Šetam u parku. – I am walking in the park. (locative)
Vidim park. – I see the park. (accusative)

Can the word order be different, like Ne želim zimi skinuti kaput u parku?

Yes. Croatian word order is relatively flexible, and you can move these elements around.

Some possible variants (all correct):

Zimi ne želim skinuti kaput u parku. (original – neutral)
Ne želim zimi skinuti kaput u parku.
Ne želim skinuti kaput u parku zimi.
U parku zimi ne želim skinuti kaput.

The differences are mostly about emphasis and rhythm:

Putting zimi first makes in winter your starting, background time frame.
Moving u parku earlier or later can highlight the place a bit more.

For a learner, the original sentence is a good neutral pattern. Other orders are fine once you feel more comfortable with Croatian syntax.

What is the difference between skinuti and skidati here?

Skinuti and skidati are the perfective / imperfective pair:

skinuti – perfective: to take off (as a single, complete action)
skidati – imperfective: to be taking off, to take off repeatedly / habitually / over time

In this sentence:

ne želim skinuti kaput
= I don’t want to (ever) take my coat off (one complete act of removing it).

If you said:

Zimi ne želim skidati kaput u parku.

it would sound more like:

I don’t want to be (repeatedly) taking my coat off in the park in winter
(e.g. every time I go there, I don’t want to keep taking it off).

Both can be correct, but skinuti fits well as the default choice: you are talking about the act of taking it off.

Why do we say ne želim skinuti and not ne želim da skinem?

In standard Croatian, after verbs like htjeti (to want), željeti (to wish/want), morati (must), moći (can), trebati (should/need), the infinitive is preferred:

Želim skinuti kaput.
Ne želim skinuti kaput.

The structure da + present tense (da skinem) is more typical and frequent in Serbian (and also in Bosnian/Montenegrin). In Croatian you can hear it, but it often sounds:

more colloquial,
or more influenced by neighboring standards.

So in Croatian the most natural form here is:

Ne želim skinuti kaput.

Why is the negation placed on želim (ne želim) and not on skinuti?

In Croatian you normally negate the finite verb (the conjugated one), not the infinitive:

Ne želim skinuti kaput. – I do not want to take my coat off.

If you said:

Želim ne skinuti kaput.

it would sound very unnatural, and even if someone understood it, it would have a strange, forced emphasis like I want to not take my coat off, which is not how native speakers phrase it.

So the pattern is:

ne + (conjugated modal verb) + infinitive
- Ne mogu skinuti kaput. – I cannot take my coat off.
- Ne želim skinuti kaput. – I don’t want to take my coat off.
- Ne smijem skinuti kaput. – I must not take my coat off.

Could I say Ja zimi ne želim skinuti svoj kaput u parku? Is that still correct, and what changes?

Yes, that sentence is grammatically correct, but it changes the style and emphasis:

Ja – adding it stresses the subject: I (as opposed to others).
svoj kaput – explicitly says my coat.

In Croatian, if it’s obvious whose coat it is (because the subject is I), you normally omit the possessive:

Zimi ne želim skinuti kaput u parku.
= In winter I don’t want to take (my) coat off in the park.

If you add the possessive, the most idiomatic choice is svoj (reflexive possessive when the possessor = subject):

Ja zimi ne želim skinuti svoj kaput u parku.

You can hear moj kaput too, but svoj is the form that grammars recommend when the subject owns the thing.

Does zimi refer to this particular winter or to winters in general?

On its own, zimi usually expresses a general, habitual situation:

Zimi ne želim skinuti kaput u parku.
≈ In winter (as a rule / generally), I don’t want to take my coat off in the park.

If you want to refer to a specific winter, you normally add a determiner:

Ove zime ne želim skinuti kaput u parku.
= This winter I don’t want to take my coat off in the park.

So: zimi by default suggests a general statement about the season, not one specific year.