Vi regner med, at filmen begynder klokken otte.

No. In this sentence, regner is not about weather.

Danish at regne can mean different things depending on context:

• det regner = it’s raining
• at regne = to calculate / count
• at regne med = to expect / assume / count on

So Vi regner med ... is a fixed expression meaning something like we expect ... or we’re assuming ....

Because regne med is an idiomatic verb phrase. You learn it as a unit:

• regne med noget
• regne med, at ...

It works a lot like English count on, where the preposition is just part of the expression. So you should think of regne med as one chunk, not as regne plus a freely chosen med.

At here means that and introduces a subordinate clause:

• Vi regner med = main clause
• at filmen begynder klokken otte = subordinate clause

So the structure is:

• We expect that the film begins at eight

In English, that is often optional. In Danish, at is very common in this kind of sentence.

Because at filmen begynder klokken otte is a subordinate clause.

In Danish, you will often see a comma before a subordinate clause, especially in teaching materials and more traditional grammar-based writing.

However, modern Danish spelling allows both:

• Vi regner med, at filmen begynder klokken otte.
• Vi regner med at filmen begynder klokken otte.

So the comma is common and correct, but in modern Danish it is not always required before at.

Because after at, Danish normally uses subordinate-clause word order, where the subject comes before the finite verb.

So you get:

• at filmen begynder ...
• subject = filmen
• verb = begynder

This is different from main clauses, where Danish follows the V2 rule and the finite verb is in second position.

Compare:

• Filmen begynder klokken otte.
  main clause

• Vi regner med, at filmen begynder klokken otte.
  subordinate clause after at

So at is a signal that the normal subordinate order is coming.

Because Danish very often uses the present tense for future meaning when the context makes the time clear.

Here, klokken otte makes it clear that we are talking about a future time, so Danish does not need a separate future form like English will begin.

This is very common in Danish:

• Jeg kommer i morgen. = I’m coming tomorrow.
• Toget går klokken seks. = The train leaves at six.
• Filmen begynder klokken otte. = The film begins at eight / will begin at eight.

Because filmen means the film, while en film means a film.

Danish usually puts the definite article at the end of the noun:

• en film = a film
• filmen = the film

So -en is the definite ending here.

This is one of the big differences from English: Danish often marks definiteness with a suffix instead of a separate word like the.

Because klokken is the normal Danish way to state clock times.

• klokken otte = at eight o’clock

Literally, klokken comes from the clock, but in modern Danish it functions as the standard time expression.

So you will very often hear:

• klokken to
• klokken halv fem
• klokken otte

English uses a preposition here, but Danish usually just uses klokken + time.

Yes, often you can.

• filmen begynder klokken otte
• filmen starter klokken otte

Both are natural and common. In many everyday situations they mean nearly the same thing.

A rough difference is:

• begynder = begins
• starter = starts

Sometimes begynder sounds a little more neutral or formal, while starter can sound slightly more everyday, but in this sentence both work well.

It is weaker.

• Vi ved ... = We know ...
• Vi regner med ... = We expect / assume ...

So Vi regner med, at filmen begynder klokken otte suggests expectation, not certainty. It means something like:

• this is what we believe will happen
• this is the plan or likely situation
• but it is not presented as a guaranteed fact

That nuance is important: regner med leaves room for uncertainty.