Learn Hardcore Norwegian: Du burde våkne tidlig i høst fordi fergen går før solen står opp. - You should wake up early this autumn because the ferry leaves before the sun rises.

Burde means “should” — a modal verb for advice or recommendation. It’s historically the past form of bør, but in modern usage it often sounds more tentative or polite. If you want a stronger obligation, you can use bør instead.

Why is there no å before våkne?

After modal verbs like burde, the main verb takes the bare infinitive (without å). So you say burde våkne, not burde å våkne.

What does i høst express, and how is it different from om høsten or denne høsten?

i høst means “this autumn” (a specific, upcoming or current period).
om høsten refers to autumn in general (every autumn), and
denne høsten also means “this autumn” but is more emphatic or formal.

How does word order work after the conjunction fordi?

In Norwegian subordinate clauses introduced by fordi, the finite verb still appears in second position within that clause. The conjunction itself doesn’t count as one of the slots, so you get:
fordi + subject (fergen) + verb (går) + rest of clause.

What does fergen mean, and how do you form the definite singular?

ferge means “a ferry.”
To form the definite singular, you add the suffix -en: ferge → fergen (“the ferry”).
You don’t need a separate article when you use the suffix.

Why is there no at before før solen står opp?

Conjunctions like før, når and mens introduce subordinate clauses directly without at. So you say før solen står opp, not før at solen står opp.

Why is opp at the end in solen står opp?

stå opp is a separable verb meaning “to rise” or “to get up.” When it’s conjugated, the particle opp moves to the end of the clause: subject (solen) + verb (står) + particle (opp).

Could you start the sentence with I høst, and how would the word order change?

Yes. If you place i høst at the beginning, you trigger inversion (V2 word order) in the main clause:
I høst burde du våkne tidlig fordi fergen går før solen står opp.
Here burde (finite verb) comes before du (subject) after the initial adverbial.