Når vejret er varmt, plejer vi at sidde på terrassen.

Når means when here. It introduces a situation that happens repeatedly or whenever something is the case:

• Når vejret er varmt = When the weather is warm / Whenever the weather is warm

A learner should not confuse it with:

• da = when for a specific event in the past
• hvis = if

So in this sentence, når is used because it describes a general habit, not one single past event.

In Danish, vejr means weather, and vejret means the weather.

Danish often uses the definite form where English uses a general noun. So:

• Vejret er varmt = The weather is warm

That sounds natural in Danish. Using just vejr here would sound incomplete or unnatural in this kind of statement.

Because vejr is a neuter noun in Danish:

• et vejr = a weather (grammatically speaking)

Adjectives in Danish often agree with the noun. With a singular neuter noun, the adjective usually takes -t:

• varm → common gender singular
• varmt → neuter singular

So:

• vejret er varmt = the weather is warm

Compare:

• en dag er varm = a day is warm
• et vejr er varmt = a weather is warm

Plejer here means usually, tend to, or are in the habit of.

So:

• plejer vi at sidde = we usually sit
• more literally: we tend to sit

This verb is very common for talking about habits:

• Jeg plejer at gå tidligt i seng. = I usually go to bed early.
• Han plejer at drikke kaffe om morgenen. = He usually drinks coffee in the morning.

So the whole sentence describes something habitual, not something happening right now.

Because pleje is normally followed by at + infinitive.

So:

• plejer at sidde = usually sit / tend to sit

This is similar to English patterns like like to sit, need to sit, though the grammar is not always identical.

Examples:

• Vi plejer at spise klokken seks. = We usually eat at six.
• Hun plejer at cykle på arbejde. = She usually cycles to work.

So the structure is:

• plejer + at + infinitive

This is because Danish is a verb-second (V2) language in main clauses.

The sentence begins with the subordinate clause:

• Når vejret er varmt

After that, the main clause must place the finite verb in the second position:

• plejer vi at sidde på terrassen

So Danish says:

• Når vejret er varmt, plejer vi at sidde på terrassen.

Not:

• Når vejret er varmt, vi plejer at sidde på terrassen. ❌

This is a very important Danish word order rule.

Because Når vejret er varmt is a subordinate clause.

In that clause, the normal order is:

• subject + verb + adjective/complement
• vejret er varmt

That part works quite similarly to English.

Then the sentence moves to the main clause, where Danish uses the V2 rule:

• plejer vi at sidde på terrassen

So the sentence contains two different clause types:

1. Subordinate clause: Når vejret er varmt
2. Main clause: plejer vi at sidde på terrassen

Because the first part is a subordinate clause, and it is followed by the main clause:

• Når vejret er varmt, plejer vi at sidde på terrassen.

The comma helps show the boundary between:

• When the weather is warm and
• we usually sit on the terrace

In modern written Danish, this comma is standard and very helpful for readability.

På usually means on, but with places like terrassen it is often the natural preposition in Danish.

So:

• på terrassen = on the terrace / out on the terrace

This is similar to:

• på altanen = on the balcony
• på stranden = at/on the beach

English and Danish prepositions do not always match exactly word for word, so it is best to learn på terrassen as a natural phrase.

It mainly talks about a general repeated situation.

• Når vejret er varmt = When/Whenever the weather is warm
• plejer vi at sidde på terrassen = we usually sit on the terrace

So it is not about one single present moment and not necessarily one specific future moment either. It describes a habit that applies whenever that condition happens.

English does something similar:

• When the weather is warm, we usually sit on the terrace.

Not in normal English. The best natural translation is:

• When the weather is warm, we usually sit on the terrace.

Or:

• When the weather is warm, we tend to sit on the terrace.

Although plejer expresses habitual action, English use to usually refers to a past habit:

• We used to sit on the terrace = a past habit, maybe no longer true

So for this Danish sentence, usually or tend to is better.

Its basic meaning is to sit, but in Scandinavian languages verbs like sidde, stå, and ligge are often used very naturally in places where English may be less specific.

Here, sidde på terrassen most likely means:

• sit out on the terrace
• be sitting on the terrace

It suggests spending time there in a seated, relaxed way. In this sentence, the simple translation sit on the terrace is perfect.