När det är kallt ute blir kinderna torra och kalla.

När means when.

It introduces a time clause: När det är kallt ute ... = When it is cold outside ...

A useful contrast is:

• när = when
• om = if

So in this sentence, it is talking about a situation that happens when the weather is cold, not a hypothetical if.

In det är kallt, det is a dummy subject, similar to English it in it is cold.

You are not talking about a specific it. It is just required by the grammar.

So:

• det är kallt = it is cold
• det regnar = it is raining

This is very common in Swedish for weather and general conditions.

Because the adjective agrees with det.

With en-words, you often get the basic adjective form:

• en kall dag = a cold day

With ett-words and with dummy det in expressions like this, the adjective often takes -t:

• ett kallt rum = a cold room
• det är kallt = it is cold

So kallt is the correct form here.

Ute means outside / outdoors.

So:

• det är kallt = it is cold
• det är kallt ute = it is cold outside

It adds location and makes the sentence sound more natural in this context.

A close alternative is utomhus, but ute is more everyday and idiomatic here.

Blir means becomes / gets.

So:

• kinderna är torra och kalla = the cheeks are dry and cold
• kinderna blir torra och kalla = the cheeks become/get dry and cold

Using blir shows a change of state. The cheeks were not necessarily dry and cold before, but cold weather causes them to become that way.

Kinderna is the definite plural of kind (cheek).

The forms are:

• en kind = a cheek
• kinden = the cheek
• kinder = cheeks
• kinderna = the cheeks

So kinderna means the cheeks.

In English, body parts are often used without sounding very definite, but Swedish commonly uses the definite form in sentences like this.

Because they agree with kinderna, which is plural definite.

Adjective agreement in Swedish often works like this:

• en torr kind = a dry cheek
• ett kallt rum = a cold room
• torra kinder = dry cheeks
• de torra kinderna = the dry cheeks

In your sentence, the adjectives come after blir, but they still describe kinderna, so plural agreement is used:

• kinderna blir torra och kalla

That is why both adjectives end in -a.

Because when a subordinate clause comes first in Swedish, the main clause follows verb-second word order.

The first part is the subordinate clause:

• När det är kallt ute

After that comes the main clause, and in a Swedish main clause the finite verb usually comes in the second position:

• blir = verb
• kinderna = subject

So you get:

• När det är kallt ute blir kinderna torra och kalla.

This is a very important Swedish pattern:

• När jag kommer hem äter jag.
• Om det regnar stannar vi hemma.

English does not do this in the same way, so it often feels unusual to learners.

Not necessarily.

In Swedish, commas are generally used less often than in English. A sentence like this is very commonly written without a comma:

• När det är kallt ute blir kinderna torra och kalla.

A comma can sometimes appear for clarity or style, but it is not required here.

So the version without a comma is completely normal.

Yes, in context it usually refers to one’s cheeks in general, even though Swedish literally says the cheeks.

This is common with body parts in Swedish. The language often uses the definite form where English might prefer a possessive.

So this sentence can naturally mean something like:

• your cheeks get dry and cold
• people’s cheeks get dry and cold

depending on context.

You could, but it would change the meaning.

• kinderna = the cheeks
• ansiktet = the face

So:

• kinderna blir torra och kalla = specifically the cheeks become dry and cold
• ansiktet blir torrt och kallt = the face becomes dry and cold

Notice that if you change the noun, the adjective endings may also change:

• ansiktet is singular and an ett-word
• so you would say torrt och kallt, not torra och kalla

Yes. In everyday English, gets is often the most natural translation.

So this sentence can be understood as:

• When it is cold outside, the cheeks get dry and cold.

That is often more natural in spoken English than become, even though become is closer to the literal grammar of bli.