Það verður smám saman myrkur úti.

Here það is a dummy subject, much like English it in It is raining or It is getting dark.

It does not refer to a specific thing. Icelandic often uses það in weather expressions and other impersonal sentences:

• Það rignir. = It is raining.
• Það er kalt. = It is cold.
• Það verður myrkur. = It gets dark.

So in this sentence, það is required by the grammar, even though it does not point to anything concrete.

Verður is from verða, which usually means to become, to get, or sometimes to happen.

That matters here because the sentence describes a change of state:

• Það er myrkur úti. = It is dark outside.
• Það verður myrkur úti. = It becomes / gets dark outside.

So verður shows that it is gradually changing from light to dark, not simply describing the current state.

Not exactly. In this sentence, verður is best understood as present tense of verða meaning becomes / gets.

So:

• Það verður myrkur úti usually means It gets dark outside
• not necessarily It will be dark outside

Icelandic does sometimes use verða to help express the future, but here it is mainly the normal verb become/get.

Verður is:

• 3rd person singular
• present tense
• from the verb verða

That matches the dummy subject það, which is grammatically singular.

A few forms of verða are:

• ég verð = I become
• þú verður = you become
• það verður = it becomes

Smám saman is a fixed adverbial phrase meaning:

• gradually
• little by little
• step by step

It is very common in Icelandic.

Historically, it comes from older inflected forms related to small or little, but for a learner the most useful thing is to treat it as a set phrase. In modern Icelandic, it is best learned as one unit:

• smám saman = gradually

Examples:

• Hann batnaði smám saman. = He gradually got better.
• Það kólnar smám saman. = It gradually gets colder.

Here myrkur is usually understood as a noun, meaning darkness or dark in the sense of dark conditions.

So the structure is roughly:

• Það verður myrkur = It becomes darkness / It gets dark

In English we normally use an adjective, but Icelandic often uses myrkur naturally in this kind of expression.

A closely related adjective is:

• myrkur = dark when describing a masculine noun
• but that is not the main point here

In this sentence, learners should mainly understand myrkur as the word used in the expression for it getting dark.

Yes. Það verður dimmt úti is also a natural sentence, and many learners compare these two:

• myrkur relates to darkness
• dimmt is the neuter form of the adjective dimur, meaning dark

In everyday usage, both can work in contexts about it getting dark outside. Very roughly:

• Það verður myrkur úti = it becomes dark outside / darkness falls outside
• Það verður dimmt úti = it gets dark outside

The difference is not huge for a beginner, but myrkur feels more like darkness, while dimmt is more directly adjectival.

Because myrkur here is being used in a general, uncountable sense: darkness.

Icelandic often does not use the definite article where English might or might not think of the. In this sentence, we are not talking about a specific darkness, just the general condition of becoming dark.

So:

• myrkur = darkness / dark
• not myrkrið = the darkness

Using myrkrið here would usually sound much less natural.

Úti means outside, outdoors, or outside there.

It is an adverb, not a noun. In this sentence it tells you where it is getting dark:

• úti = outside

Putting it at the end is very natural in Icelandic:

• Það verður smám saman myrkur úti.

The sentence could sometimes be rearranged for emphasis, but this order is straightforward and idiomatic.

Also note the difference between:

• úti = outside, in an outdoor location
• út = out, outward, involving motion

So here úti is correct because this is a location, not movement.

Yes, Icelandic word order is somewhat flexible, especially with adverbs. But not every version sounds equally neutral.

The given sentence:

• Það verður smám saman myrkur úti.

is a very natural neutral order.

You may also see variations such as:

• Smám saman verður myrkur úti.
• Það verður myrkur úti smám saman.

These can shift the emphasis slightly:

• starting with smám saman highlights the gradual process more
• putting it later can make it feel like an added time/manner detail

For beginners, the original order is a good model to learn.

As a predicate complement after verða, it is best thought of as standing in the nominative.

However, with myrkur, the form does not visibly show much difference here, because neuter singular forms can look the same.

So the important practical point is:

• after vera and verða, predicate nouns are commonly nominative

Even if the form itself does not make that obvious in this sentence, that is the usual grammatical analysis.

A rough pronunciation guide is:

• Það ≈ thath
• verður ≈ VEHR-thur
• smám saman ≈ smaum SAH-man
• myrkur ≈ MIRK-ur
• úti ≈ OOH-ti

A few useful pronunciation notes:

• ð in það and verður is like the th in this
• þ would be like the th in thin, but there is no þ in this sentence
• y in myrkur is pronounced like Icelandic i, not like English y
• ú is a long oo sound

A more natural rhythm would stress:

• VERÐUR
• SMÁM
• MYRKUR
• ÚTI

A helpful literal breakdown is:

• Það = dummy it
• verður = becomes / gets
• smám saman = gradually
• myrkur = darkness / dark
• úti = outside

So the structure is basically:

It becomes gradually dark outside.

That is not the best natural English wording, but it shows how the Icelandic sentence is built.