Når det holder op med at regne, går jeg ud med min hund.

Når means when in the sense of a repeated or general situation, or something expected in the future.

In this sentence, Når det holder op med at regne means When it stops raining.

A very important contrast is:

• når = when for something habitual, general, or future
• da = when for a specific event in the past

So Danish uses når here because the sentence is talking about what happens whenever the rain stops, not about one finished past event.

The det is an impersonal or dummy subject.

Danish, like English, often needs a subject even when there is no real person or thing doing the action. Weather expressions commonly use det:

• Det regner = It is raining
• Det sner = It is snowing

In det holder op med at regne, the det works in the same general weather-style way. English does something similar with it in it stops raining.

This is the normal Danish structure for to stop doing something:

• holde op med at + infinitive

So:

• holde op med at regne = stop raining
• holde op med at ryge = stop smoking
• holde op med at tale = stop talking

Here is the breakdown:

• holder op = stops / ceases
• med = part of the fixed expression
• at regne = to rain

You usually learn holde op med at as one chunk.

This is because Danish is a verb-second language in main clauses.

If something other than the subject comes first, the finite verb must come next. In this sentence, the whole Når clause comes first:

• Når det holder op med at regne, ...

So the main clause must begin with the verb:

• går jeg ud med min hund

Basic pattern:

• Jeg går ud med min hund.
• Når det holder op med at regne, går jeg ud med min hund.

The first version starts with the subject, so normal subject-verb order is used.
The second version starts with a subordinate clause, so the verb comes before the subject in the main clause.

That part is a subordinate clause, and Danish subordinate clauses normally keep the subject before the verb:

• det = subject
• holder = finite verb
• op med at regne = rest of the verbal expression

So the order is:

• Når + subject + verb + ...

This is different from the main clause, where verb-second applies.

Literally, går comes from gå, which often means walk or go on foot. But in this sentence, går ud is best understood as go out.

So:

• gå ud = go outside / go out

Then:

• gå ud med hunden or gå ud med min hund often means go out with the dog, and very often in real life it implies take the dog out for a walk.

So the exact English wording depends on context, but the Danish expression is very natural.

Because gå ud is a common verb + particle combination meaning go out or go outside.

Danish often uses short particles like this:

• gå ud = go out
• gå ind = go in
• stå op = get up
• komme hjem = come home

So ud is not random; it is an important part of the expression.

Min hund means my dog.

A few useful points:

• hund is a common-gender noun
• min is the possessive used with common-gender singular nouns
• the indefinite singular form is en hund
• therefore: min hund

Compare:

• en hund = a dog
• hunden = the dog
• min hund = my dog

If the noun were neuter, you would use mit instead of min.

Danish often uses the present tense for future meaning, especially when the time is clear from the context.

So:

• Når det holder op med at regne, går jeg ud med min hund

can refer to what I generally do, or what I will do once the rain stops.

English does something similar in time clauses:

• When it stops raining, I go out with my dog
• When it stops raining, I’ll go out with my dog

Danish very often does not need a special future form here.

Yes, in standard Danish writing, a subordinate clause like the one introduced by Når is separated from the main clause with a comma:

• Når det holder op med at regne, går jeg ud med min hund.

This comma helps show where the subordinate clause ends and the main clause begins.

Yes, many speakers do use så in sentences like this:

• Når det holder op med at regne, så går jeg ud med min hund.

The så adds a kind of then feeling. It is often natural in speech, but it is not necessary.

So both are possible:

• Når det holder op med at regne, går jeg ud med min hund.
• Når det holder op med at regne, så går jeg ud med min hund.

The version without så is perfectly normal and slightly more neutral.

Yes, that is also possible, but it is a slightly different structure.

• Når det holder op med at regne = when it stops raining
• Når det er holdt op med at regne = when it has stopped raining

The second version sounds a bit more completed or result-focused. The original sentence is very natural and probably the most straightforward version for everyday use.

A rough guide is:

• regne sounds approximately like RINE-uh or RHINE-uh, but with a Danish r and a softer final vowel
• in actual speech, the second syllable is very weak

Also, Danish pronunciation is often less clearly spelled out than English learners expect, so it is best to hear it from native audio if possible.

A rough full-sentence pronunciation guide would be something like:

• Nore de holder op me at rine, gor yai oo me min hun

But that is only a rough approximation. Danish pronunciation is much easier to learn from listening than from English-style spelling.