Vindurinn blæs suður.

It is vindur + the definite ending -inn.

• vindur = wind
• vindurinn = the wind

So vindurinn is the definite singular form of the noun.

Because Icelandic usually adds the definite article to the end of the noun instead of putting a separate word before it.

So where English says:

• the wind

Icelandic often says:

• vindurinn

There is also a separate article in Icelandic in some contexts, but in ordinary sentences like this, the suffixed article is the normal choice.

It is nominative singular.

That is because vindurinn is the subject of the sentence, and subjects are normally in the nominative case in Icelandic.

So here:

• vindurinn = the subject
• blæs = the verb
• suður = an adverb of direction

Blæs is the present tense singular form of blása, meaning to blow.

In this sentence it is the 3rd person singular, matching vindurinn (the wind), which is singular.

A few present-tense forms are:

• ég blæs = I blow
• þú blæst = you blow
• hann / hún / það blæs = he / she / it blows
• við blásum = we blow

Yes, it is not completely regular.

Its forms involve stem changes, for example:

• infinitive: blása
• present: blæs
• past: blés
• past participle: blásið

So it is a verb worth memorizing as a pattern, not just by adding endings mechanically.

Here suður is an adverb of direction.

It means something like southward or to the south, not an adjective like southern.

That is why it works directly after the verb:

• Vindurinn blæs suður.

Other direction words can work in the same way:

• norður = northward
• austur = eastward
• vestur = westward

Because Icelandic often uses these direction words by themselves as adverbs.

English often prefers expressions like to the south, but Icelandic can simply say:

• suður = southward / to the south

So blæs suður is structurally normal in Icelandic.

By itself, suður normally expresses direction toward the south.

If you want to say from the south, Icelandic would usually use a different expression, such as:

• úr suðri = from the south

So the bare form suður is directional, not an origin phrase.

Yes. This is a very normal order:

• Vindurinn = subject
• blæs = finite verb
• suður = adverbial/directional element

So it follows a basic subject + verb + adverbial pattern.

More generally, Icelandic is a verb-second language, which means the finite verb often stays in second position if something else is placed first. For example:

• Í dag blæs vindurinn suður. = Today the wind blows south.

A rough English-friendly approximation is:

• Vindurinn ≈ VIN-du-rin
• blæs ≈ blice or bl-ice
• suður ≈ SUE-thur, with th like in this

A few helpful notes:

• æ in blæs sounds roughly like the vowel in eye
• ð in suður is like th in this
• the Icelandic r is usually trilled or tapped, not the typical English r

The English approximation is only rough, but it can help you get started.