Ég ætla að kíkja á veðurspána áður en við förum út.

Ætla að + infinitive is a very common way to express intention or a near-future plan in Icelandic.

So Ég ætla að kíkja means something like:

• I’m going to check
• I intend to check
• I’m about to take a look

Icelandic does not rely on a single future tense the way English uses will. Very often, future meaning is expressed with the present tense or with constructions like ætla að.

Because ætla normally takes an infinitive with að.

So the pattern is:

• ætla að gera eitthvað = intend to do something

Here:

• ætla að kíkja = intend to check / am going to check

This að is the infinitive marker, similar to English to in to check.

Kíkja á is an idiomatic expression meaning:

• take a quick look at
• check
• have a look at

So kíkja á veðurspána is very natural Icelandic for check the weather forecast.

The verb kíkja by itself can mean something like peek or look in, but in everyday speech kíkja á is often just a casual way to say look at/check.

Yes, kíkja is somewhat more conversational than a more neutral verb like skoða or athuga.

In this sentence, kíkja á veðurspána sounds very natural and everyday, like:

• I’m going to check the forecast
• I’ll just have a look at the forecast

If you wanted a slightly less casual tone, you could also say:

• Ég ætla að athuga veðurspána
• Ég ætla að skoða veðurspána

But the original sentence sounds completely normal.

Because veðurspána is the definite accusative singular form of veðurspá.

Here is the basic idea:

• veðurspá = weather forecast (indefinite)
• veðurspáin = the weather forecast (nominative)
• veðurspána = the weather forecast (accusative)

In this sentence, the noun is the object of kíkja á, so Icelandic uses the accusative form.

So:

• á veðurspána = at / on the weather forecast in form, but really check the weather forecast in meaning

In this sentence, it is best to learn the whole expression kíkja á + accusative.

So yes, the noun after á here appears in the accusative, but this is not mainly the usual motion vs. location rule that learners often meet with á. Instead, this is part of the verb expression itself:

• kíkja á eitthvað = check/look at something

A good way to learn it is as one unit, just like English look at.

Áður en means before.

It introduces a subordinate clause:

• áður en við förum út = before we go out

It is best to learn áður en as a fixed expression. Even though en can mean other things in other contexts, here the two words together simply function as before.

Because Icelandic often uses the present tense in time clauses, even when the meaning is future.

English does this too:

• before we go out
  not usually
• before we will go out

So:

• áður en við förum út literally looks like before we go out
• but the meaning is future because of the context

The future sense of the whole sentence comes from ætla að and from the situation being described.

Förum is the 1st person plural present form of fara (to go):

• ég fer = I go
• við förum = we go

So við förum út means we go out / we’re going out.

One small extra point: in this person and number, the present indicative and present subjunctive forms happen to look the same, so the sentence does not visibly show a distinction there. For a learner, the main thing to recognize is simply that förum is the we form of fara.

Because út expresses movement outward, while úti expresses location outside.

Compare:

• við förum út = we go out
• við erum úti = we are outside

So in this sentence, since the idea is moving from inside to outside, út is the correct choice.

Here it means we.

That is because við is the subject of förum:

• við förum = we go

Icelandic við can also be a preposition meaning with / by / against, but in that case it would be followed by another word or phrase, for example:

• við hann = with him
• við húsið = by the house

In your sentence, it is clearly the pronoun we.

Yes. You can absolutely say:

• Áður en við förum út ætla ég að kíkja á veðurspána.

That means the same thing.

The important thing to notice is the word order in the main clause after the fronted subordinate clause:

• Áður en við förum út ætla ég ...
• not Áður en við förum út ég ætla ...

This is because Icelandic follows a verb-second pattern in main clauses. When something else comes first, the finite verb usually comes before the subject in the main clause.

Not perfectly. Some parts match neatly, but some are more idiomatic.

A rough word-by-word breakdown is:

• Ég = I
• ætla að = intend to / am going to
• kíkja á = look at / check
• veðurspána = the weather forecast
• áður en = before
• við = we
• förum = go
• út = out

But the most natural English translation will usually smooth things out a little, because kíkja á and ætla að are not always translated literally word-for-word.