Framrúðan var svo skítug í morgun að ég sá varla út.

Framrúðan is a compound noun:

• fram- = front
• rúða = pane, window, glass

So framrúða literally means front window/pane, which is the usual Icelandic word for a car’s windshield.

The ending -n is the suffixed definite article, so:

• framrúða = a windshield
• framrúðan = the windshield

A useful extra point: in Icelandic compounds, the gender usually comes from the last part of the word. Since rúða is feminine, framrúða is feminine too.

Because the adjective agrees with framrúðan, which is feminine singular.

Here the adjective is used predicatively, after var:

• Framrúðan var skítug = The windshield was dirty

The adjective still matches the subject in gender and number:

• masculine: skítugur
• feminine: skítug
• neuter: skítugt

Since framrúðan is feminine singular, skítug is the correct form.

Svo ... að means so ... that.

In this sentence:

• svo skítug ... að = so dirty that

So the structure is:

• Framrúðan var svo skítug ... að ég sá varla út.
• The windshield was so dirty ... that I could barely see out.

This is a very common Icelandic construction.

Yes. Í morgun commonly means this morning.

It is an idiomatic time expression, not something you should translate word for word too mechanically.

A very useful contrast is:

• í morgun = this morning
• á morgun = tomorrow

Those two are easy to mix up, but they mean completely different things.

Var is the past tense of vera = to be.

So:

• er = is
• var = was

The sentence is describing a state in the past:

• Framrúðan var skítug = The windshield was dirty

It is not using verða = become. If Icelandic wanted to say became dirty, that would involve forms of verða, not vera.

Sá is the past tense of sjá = to see.

This verb is irregular, so the forms change quite a bit:

• infinitive: sjá
• present: ég sé = I see
• past: ég sá = I saw

So in the sentence:

• ég sá varla út = I barely saw out / I could barely see out

Even though sá looks very different from sjá, it is just the normal past-tense form.

Varla means barely, hardly, or scarcely.

So:

• ég sá varla út = I could barely see out

It weakens the verb and shows that something was almost not possible.

You will often see varla with verbs:

• Ég heyri varla. = I can barely hear.
• Hann gat varla talað. = He could hardly speak.

Yes. Here út means out / outside, and with sjá it gives the sense of see out or see outside.

So:

• sjá út = see out
• sjá út um gluggann = see out through the window

In this sentence, the object is not stated because it is obvious from context: we are talking about looking out through the windshield.

Icelandic often expresses this idea without a separate modal verb.

Literally, ég sá varla út is I barely saw out, but natural English usually says:

• I could barely see out

So the sense of ability is understood from the situation. Icelandic does not always need an equivalent of English could when the context already makes that meaning clear.

It is somewhat vivid and colloquial, but very common in everyday speech.

It comes from skítur, and depending on context it can feel stronger than a very neutral word like óhreinn / óhrein / óhreint = unclean. In ordinary conversation, though, skítugur / skítug / skítugt is often just a normal way to say dirty or filthy.

So in this sentence it does not sound shocking; it just emphasizes that the windshield was really dirty.