Ég fer stundum í sandölum og með sólgleraugu heim úr vinnu þegar veðrið er heitt.

Fara usually means to go in a general sense. In a sentence like this, Ég fer ... heim úr vinnu means I go home from work.

It does not specifically tell you how the person goes. They might walk, drive, take the bus, and so on. If you wanted to say specifically I walk home, you would more likely use ganga:

• Ég geng heim úr vinnu = I walk home from work

So fer is the normal broad verb here.

Stundum means sometimes.

Its position is very natural in Icelandic. In a simple main clause, adverbs like stundum often come after the finite verb:

• Ég fer stundum ... = I sometimes go ...

You may see some variation in word order for emphasis, but this placement is very common and neutral.

Here í sandölum means in sandals / wearing sandals.

The preposition í can take different cases:

• accusative when it means movement into
• dative when it means location/state

In this sentence, the meaning is not going into sandals, but being in sandals / wearing sandals, so Icelandic uses the dative.

That is why you get:

• singular: í sandala? No, that would not be the right form here
• plural dative: í sandölum

So the grammar is:

• sandalar = sandals
• sandölum = dative plural

This is one of those places where Icelandic and English package things differently.

Icelandic very often uses í with clothes that you are wearing:

• í jakka = in a jacket
• í skónum = in the shoes
• í sandölum = in sandals

English can also say in sandals, so this one is actually not too far from English usage. The idea is that the person is dressed in or wearing that item.

Með means with, and Icelandic often uses it for accessories or things a person has on them, including glasses:

• með sólgleraugu = with sunglasses / wearing sunglasses

This is very natural Icelandic.

Also, með takes the accusative, and sólgleraugu is the accusative plural form here.

So:

• í sandölum = in sandals
• með sólgleraugu = with sunglasses

That combination sounds quite normal.

Sólgleraugu means sunglasses, and like gleraugu for glasses, it is normally treated as a plural-only noun.

So Icelandic usually talks about sunglasses as a plural item, much like English does.

Some useful forms are:

• sólgleraugu = sunglasses
• með sólgleraugu = with sunglasses
• í sólgleraugum = in glasses / wearing glasses

In this sentence, the form stays sólgleraugu because með takes the accusative, and that accusative plural form looks the same here.

Because heim is an adverb meaning homeward / home.

Icelandic often says simply:

• fara heim = go home
• koma heim = come home

This works a lot like English, where we also usually say go home, not go to home.

So in the sentence:

• heim úr vinnu = home from work

heim gives the destination, and úr vinnu gives the starting point.

Both úr and frá can relate to from, but they are not always used the same way.

• úr often has the sense of out of
• frá is a more general from

With places like work or school, úr vinnu and úr skóla are very common when talking about leaving them:

• fara heim úr vinnu = go home from work
• koma úr skóla = come from school

So úr vinnu is a very natural phrase here.

Also, úr takes the dative, which is why the noun is in that case.

After úr, Icelandic uses the dative case.

So in úr vinnu, vinnu is in the dative singular.

For this noun, some forms happen to look the same, so you do not immediately see a dramatic change. But grammatically, the reason is still:

• úr
  • dative

That is the key rule.

This is a subordinate clause introduced by þegar, which means when.

So:

• þegar = when
• veðrið = the weather
• er = is
• heitt = warm/hot

Together:

• þegar veðrið er heitt = when the weather is warm/hot

A useful thing to notice is word order. In a subordinate clause after þegar, Icelandic does not use the main-clause verb-second pattern. So the subject comes naturally before the verb:

• þegar veðrið er heitt

not something like a main-clause inversion pattern.

Veðrið is the definite form, meaning the weather.

That is the normal way to say it in this kind of sentence:

• þegar veðrið er heitt = when the weather is warm

Using the definite form here is very natural, just as English also normally says the weather.

Because heitt has to agree with veðrið.

Veðrið is:

• neuter
• singular

Predicate adjectives in Icelandic agree with the noun they describe, so the adjective must also be neuter singular:

• heitur = masculine singular
• heit = feminine singular
• heitt = neuter singular

Since veðrið is neuter, heitt is the correct form.

Yes. Icelandic word order is fairly flexible, especially with adverbials like stundum, heim úr vinnu, and phrases describing what someone is wearing.

For example, a sentence like this could also be rearranged in natural ways depending on emphasis. But the original order is perfectly normal:

• Ég fer stundum í sandölum og með sólgleraugu heim úr vinnu þegar veðrið er heitt.

This version puts the focus first on the fact that the speaker goes wearing sandals and sunglasses, and then gives the destination home from work.

So the word order is not random, but it is also not the only possible one.