Það er alveg kalt úti.

A natural word-by-word breakdown is:

• Það = it
• er = is
• alveg = quite / really / completely
• kalt = cold
• úti = outside / outdoors

So the sentence is built very similarly to English: It is really cold outside.

In sentences about weather, general conditions, time, and similar ideas, Icelandic often uses það as a dummy subject, just like English uses it in it is cold.

So in this sentence, það does not refer to a specific thing. It is just there because the sentence needs a subject.

This is very common in Icelandic:

• Það er kalt. = It is cold.
• Það er heitt. = It is hot.
• Það er dimmt. = It is dark.

Kalt is the neuter singular form of the adjective kaldur.

Adjectives in Icelandic change form to match what they describe. In weather expressions like this, the adjective is usually put in the neuter singular form because it goes with the dummy subject það.

So:

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

Here, Icelandic uses kalt, not kaldur.

In this sentence, alveg works as an intensifier. It makes kalt stronger.

So alveg kalt can mean things like:

• quite cold
• really cold
• absolutely cold

In everyday use here, really cold or quite cold is usually the best way to understand it.

Be aware that alveg can also mean completely in other contexts, so its exact force depends on the sentence.

No, it is not strictly necessary.

You can say:

• Það er kalt. = It is cold.
• Það er kalt úti. = It is cold outside.

Adding úti makes the location explicit. It tells you that the cold is outside, not just in general.

This is especially useful if you want to contrast it with indoors:

• Það er kalt úti en hlýtt inni. = It is cold outside but warm inside.

Yes.

• mjög kalt = very cold
• alveg kalt = often really / quite cold

They are similar, but not identical.

Mjög is a straightforward degree word meaning very.
Alveg can sound a bit more conversational or emphatic, and its exact strength depends more on context.

So both are possible, but they are not always perfect substitutes.

Yes, but Það er alveg kalt úti is the most neutral, straightforward order.

You may also see:

• Úti er alveg kalt. = Outside, it is really cold.
• Það er kalt úti. = It is cold outside.

Fronting úti gives it more emphasis. The original sentence is the most natural choice if you are simply stating the fact.

A few useful pronunciation points:

• þ is like the th in thing
• ð is a soft sound, somewhat like the th in this, though in everyday speech it can be very light
• ú is a long oo sound, like in food

So a learner-friendly approximation would be:

• það ≈ thahth or sometimes almost thah
• úti ≈ oo-ti

You do not need to pronounce every sound perfectly at first. The most important thing is to get:

• þ different from t
• ú as a long oo
• kalt with a clear k and t

Yes, very much so.

This pattern is extremely useful:

Það er + adverb + adjective + place word

Examples:

• Það er mjög heitt úti. = It is very hot outside.
• Það er dimmt inni. = It is dark inside.
• Það er frekar hlýtt hérna. = It is rather warm here.
• Það er rosalega vindasamt úti. = It is terribly windy outside.

So Það er alveg kalt úti is a great model sentence for talking about weather and general conditions.

Usually yes, but it is often best thought of as outdoors or outside in a broad sense.

It is commonly used in everyday Icelandic to talk about conditions beyond the house, building, or enclosed space:

• Krakkarnir eru úti. = The children are outside.
• Það er kalt úti. = It is cold outside.

A common opposite is inni = inside.

So úti is a very practical everyday word, and this sentence is a good example of how it is used.