Det ser ut til å bli kaldt i kveld.

Here, det is a dummy subject or formal subject. It does not refer to a specific thing.

Norwegian often uses det in weather expressions and in general statements, much like English it in:

• It is cold
• It looks like rain
• It seems strange

So in Det ser ut til å bli kaldt i kveld, det is just the grammatical subject needed to make the sentence work.

Ser ut til means looks like or seems likely to.

It is a very common expression in Norwegian:

• Det ser ut til å regne. = It looks like it’s going to rain.
• Hun ser ut til å være trøtt. = She looks/seems to be tired.

In your sentence, ser ut til å bli means looks like it’s going to become / looks like it will be.

A useful way to learn it is as a chunk:

det ser ut til å + infinitive

Because bli is in the infinitive form.

The pattern is:

ser ut til å + infinitive

So:

• å bli = to become / to get
• å regne = to rain
• å være = to be

Examples:

• Det ser ut til å regne.
• Det ser ut til å bli sent.
• Det ser ut til å være vanskelig.

The å is the normal infinitive marker, like English to.

Bli literally means become, but in weather and similar expressions it often corresponds to English be/get.

So:

• å være kald = to be cold
• å bli kald = to become cold / to get cold

In this sentence, å bli kaldt suggests a change: it is going to turn cold later.

That is why bli fits well with i kveld:

• Det er kaldt i kveld. = It is cold tonight.
• Det ser ut til å bli kaldt i kveld. = It looks like it’s going to get / be cold tonight.

English often uses be where Norwegian prefers bli.

Because the adjective is being used in a way that requires the neuter/neutral form.

After verbs like være, bli, se ut til å bli, adjectives often appear in the -t form when the subject is the dummy subject det in general statements like weather, conditions, or situations:

• Det er kaldt.
• Det blir mørkt.
• Det er fint ute.

So:

• kald = common-gender form / dictionary form
• kaldt = neuter form, and also the normal form in expressions like det er kaldt

This is very common in weather language.

I kveld means tonight or this evening, depending on context.

Literally:

• i = in
• kveld = evening

But as a time expression, i kveld is usually translated naturally as tonight.

Examples:

• Vi sees i kveld. = See you tonight.
• Det blir sent i kveld. = It will be late tonight.

So in your sentence, i kveld tells you when it will get cold.

Yes, ut belongs with ser in the expression ser ut til.

This is one of those multi-word verb expressions where the parts can stay together or be separated depending on sentence structure.

In the basic sentence:

• Det ser ut til å bli kaldt i kveld.

the words stay together naturally.

But if another element comes first, Norwegian still follows the V2 rule (the finite verb comes second), and the parts may look more spread out:

• I kveld ser det ut til å bli kaldt.

Here, ser is in second position, while det comes after it, and ut remains part of the expression.

So yes, learn se ut til å as one unit, even though word order can make it look split up.

In some spoken Norwegian, you may hear ser ut å. But the standard written form is:

ser ut til å

So for learners, the safest and best form to use is:

Det ser ut til å bli kaldt i kveld.

That is the form you should expect in careful writing and standard teaching materials.

They are very similar, but not exactly identical.

• Det ser ut til å bli kaldt i kveld = It looks like it’s going to be cold tonight.
• Det kommer til å bli kaldt i kveld = It is going to be cold tonight.

The first one suggests an impression based on signs or evidence: maybe the temperature is dropping, the sky looks clear, the forecast suggests it, and so on.

The second one is a more straightforward future statement or prediction.

So ser ut til often feels a little softer or more observational.

Yes. Norwegian often moves time expressions to the front of the sentence.

If you front i kveld, the finite verb must still come second because of the V2 rule:

• Det ser ut til å bli kaldt i kveld.
• I kveld ser det ut til å bli kaldt.

Notice what changed:

• I kveld moved to the front.
• ser stays in second position.
• det moves after the verb.

This kind of word order change is very common in Norwegian.

Yes, definitely. It is very useful to learn it as a full pattern:

Det ser ut til å + infinitive

Examples:

• Det ser ut til å regne. = It looks like it’s going to rain.
• Det ser ut til å bli vanskelig. = It looks like it’s going to be difficult.
• Det ser ut til å gå bra. = It looks like it’s going to go well.

If you memorize the pattern as a chunk, it becomes much easier to build similar sentences naturally.