Af hverju er veðrið svona kalt?

Yes. Af hverju is a very common everyday way to say why in Icelandic.

Literally, it is made up of:

• af = from / of
• hverju = the dative form of hvað = what

So historically it is something like from what? or because of what?, but in normal modern Icelandic it simply means why.

A slightly more formal alternative is hvers vegna.

Because this is a question.

Icelandic usually puts the finite verb early in direct questions. After the question phrase af hverju, you get:

• Af hverju er veðrið svona kalt?

This is similar to English Why is the weather so cold?

In a statement, the order would be:

• Veðrið er svona kalt. = The weather is this/so cold.

So the question changes the word order.

Because veðrið means the weather, while veður means just weather.

Icelandic usually adds the definite article to the end of the noun instead of using a separate word like English the.

So:

• veður = weather
• veðrið = the weather

That -ið is the definite article attached to the noun.

Veður is a neuter noun.

That matters because adjectives in Icelandic often agree with the noun they describe. Since veðrið is neuter singular, the adjective is also in the neuter singular form:

• kalt = neuter singular
• compare:
  • kaldur = masculine singular
  • köld = feminine singular
  • kalt = neuter singular

So veðrið ... kalt matches correctly.

Because kalt is the correct predicate adjective form for a neuter singular noun.

In this sentence, kalt comes after er, so it is a predicate adjective:

• veðrið er kalt = the weather is cold

Since veðrið is neuter singular, the adjective must also be neuter singular:

• kaldur = masculine
• köld = feminine
• kalt = neuter

Kalda would be used in other grammatical situations, not here.

Here svona means something like like this, this way, or very naturally in English, so.

So:

• svona kalt = this cold / so cold

In this sentence, the most natural English translation is so cold.

Svona is very common in Icelandic and is often used where English would say:

• like this
• so
• this kind of

Its exact meaning depends on context.

Yes, absolutely.

• Af hverju er veðrið kalt? = Why is the weather cold?
• Af hverju er veðrið svona kalt? = Why is the weather so cold?

Adding svona gives the sentence more emphasis. It suggests that the speaker thinks the weather is unusually cold.

A rough learner-friendly pronunciation is:

• veðrið ≈ VEH-thrith or VEH-thridh

A few important points:

• ð in Icelandic is like the th in this, not the th in thin
• the r is usually a rolled or tapped r
• the ending -ið can be tricky for English speakers, and the exact sound can vary a bit in connected speech

The main thing is to avoid pronouncing ð like a hard English d.

A rough approximation is:

• hverju ≈ KVER-yu or HVER-yu, depending on how carefully it is pronounced

Things to notice:

• hv in modern Icelandic is often pronounced close to kv
• j in Icelandic sounds like English y
• u here is not like English oo; it is a different Icelandic vowel

So af hverju may sound a bit closer to ahv KVER-yu than an English speaker first expects.

They both mean why, but they differ a little in style.

• Af hverju = very common, everyday, conversational
• Hvers vegna = also common, but often feels a bit more formal or careful

So you could also say:

• Hvers vegna er veðrið svona kalt?

That means the same thing.

Because Icelandic does not use do-support the way English does.

In English:

• Why is the weather so cold?
• but with many verbs: Why does it rain so much?

English often needs do/does/did in questions. Icelandic does not do that. It just uses the actual verb directly.

So Icelandic simply says:

• Af hverju er veðrið svona kalt?

No extra helper verb is needed.

Usually no. Veður normally means weather, not climate.

If you want climate, the usual word is:

• loftslag

So:

• veður = weather
• loftslag = climate

That means veðrið here is specifically the weather.

Yes, very natural.

Af hverju er veðrið svona kalt? sounds like something a native speaker could easily say in normal conversation. It is simple, idiomatic, and grammatically standard.

A few equally natural variations would be:

• Af hverju er svona kalt? = Why is it so cold?
• Hvers vegna er veðrið svona kalt? = same meaning, slightly more formal

So the original sentence is a very good model to learn from.