Hvis det blæser, bliver vi hjemme.

Yes—here hvis means if.

It introduces a condition:

• Hvis det blæser, bliver vi hjemme.
• If it’s windy, we stay home / we’ll stay home.

In sentences like this, hvis works very much like English if in conditional sentences.

A useful comparison:

• hvis = if
• når = when (used when something is expected or habitual rather than uncertain)

So:

• Hvis det blæser = If it’s windy / If the wind is blowing
• Når det blæser = When it’s windy / Whenever it’s windy

The first sounds conditional; the second sounds more general or expected.

In det blæser, det does not refer to a specific thing. It is an impersonal subject, similar to English it in weather expressions:

• It rains
• It snows
• It’s windy

Danish does the same kind of thing:

• det regner = it’s raining
• det sner = it’s snowing
• det blæser = it’s windy / the wind is blowing

So det here is not the wind. It is just the grammatical subject required by the sentence.

Danish often expresses weather with a verb, where English may use an adjective.

So:

• det blæser literally = it blows
• natural English meaning = it’s windy

This is a very common Danish pattern. A few examples:

• det regner = it’s raining
• det sner = it’s snowing
• det fryser = it’s freezing

You can also say something with an adjective, for example:

• Det er blæsende = It is windy

But det blæser is very common and idiomatic.

Because Danish very often uses the present tense to talk about the future, especially when the future meaning is clear from context.

So:

• bliver vi hjemme literally = stay we home / we stay home
• natural English translation = we’ll stay home

The future meaning is understood because the sentence is conditional: If it’s windy, ...

This is very normal in Danish. For example:

• I morgen rejser vi = Tomorrow we leave / we’re leaving tomorrow
• Hvis det regner, tager jeg bussen = If it rains, I’ll take the bus

Danish can use explicit future forms too, but the present tense is often the most natural choice.

Blive hjemme is a fixed expression meaning stay home.

• vi bliver hjemme = we stay home / we’ll stay home

This is slightly different from er hjemme:

• vi er hjemme = we are at home
• vi bliver hjemme = we remain at home / we do not go out

So in this sentence, bliver hjemme emphasizes the decision not to leave.

Compare:

• Vi er hjemme nu. = We are home now.
• Vi bliver hjemme i aften. = We’re staying home tonight.

This is because the sentence begins with a subordinate clause:

• Hvis det blæser = If it’s windy

When that whole clause comes first, it takes the first position in the sentence. In a Danish main clause, the finite verb must then come before the subject. This is the normal V2 pattern in Danish.

So the structure is:

• Hvis det blæser,
  • bliver vi hjemme
• conditional clause first, then main clause with verb before subject

That is why you get:

• bliver vi hjemme

and not:

• vi bliver hjemme

Compare:

• Vi bliver hjemme, hvis det blæser.

  • Here the main clause comes first, so normal order is vi bliver hjemme.

• Hvis det blæser, bliver vi hjemme.

  • Here the hvis clause comes first, so the main clause becomes bliver vi hjemme.

Yes, in normal Danish writing you write a comma after the initial hvis clause:

• Hvis det blæser, bliver vi hjemme.

The comma separates the subordinate clause from the main clause.

So the sentence is divided like this:

• Hvis det blæser = subordinate clause
• bliver vi hjemme = main clause

For a learner, it is a good habit to write the comma in sentences like this.

Yes, that is grammatically correct.

• Hvis det er blæsende, bliver vi hjemme.
• Hvis det blæser, bliver vi hjemme.

Both are possible, but they are not exactly the same in feel:

• det blæser focuses on the wind actually blowing
• det er blæsende describes the weather as windy

In many everyday contexts, det blæser sounds more natural and common.

Danish usually does not need an equivalent of then in this kind of conditional sentence.

So:

• Hvis det blæser, bliver vi hjemme.

is already complete and natural.

You may sometimes see or hear extra words for emphasis in other contexts, but in ordinary Danish, the basic if + clause, main clause structure works fine without anything corresponding to then.

Yes. You can also say:

• Vi bliver hjemme, hvis det blæser.

This means the same thing.

The difference is mainly in emphasis and word order:

• Hvis det blæser, bliver vi hjemme.

  • starts with the condition
  • main clause uses verb-subject order: bliver vi

• Vi bliver hjemme, hvis det blæser.

  • starts with the result/main statement
  • main clause uses normal subject-verb order: vi bliver

Both are completely natural.

In careful speech, bliver is pronounced something like BLI-ver.

But in everyday spoken Danish, it is often reduced, and you may hear something closer to:

• bli’r

So:

• vi bliver hjemme

may sound more like:

• vi bli’r hjemme

That is very common in speech. In writing, however, you normally write bliver.