Μπορεί να βρέξει αργότερα, γιατί η ομίχλη δεν φεύγει από το πρωί.

Because Greek is choosing between two different aspects:

• να βρέξει = aorist subjunctive → a single event, or rain starting/happening at some point
• να βρέχει = present subjunctive → ongoing rain, continuous action

So Μπορεί να βρέξει αργότερα means It may rain later, referring to rain as a possible event in the future.

If you said Μπορεί να βρέχει, that would more naturally mean something like It may be raining or it may rain continuously, depending on context.

Here μπορεί να means may / might / could in the sense of possibility.

Literally, μπορεί comes from μπορώ = I can / it is possible, so the whole expression μπορεί να... means it may be that... or it is possible that...

So:

• Μπορεί να βρέξει = It may rain
• Μπορεί να έρθει = He/She may come

It is a very common Greek way to express possibility.

Because να introduces the subjunctive in Modern Greek.

After expressions like:

• μπορεί να = may
• θέλω να = I want to
• πρέπει να = must
• ελπίζω να = I hope to / that

Greek normally uses να + verb.

So in this sentence:

• μπορεί να βρέξει = it may rain

English does not have a direct equivalent word here, so it can feel strange at first. But in Greek, να is completely normal and necessary in this structure.

Αργότερα means later.

In this sentence:

• Μπορεί να βρέξει αργότερα = It may rain later

It is the comparative form related to αργά (late / slowly, depending on context), but as an adverb αργότερα is very often just used to mean later.

Greek uses the definite article much more often than English.

So η ομίχλη literally means the fog, and that sounds natural in Greek even when English might simply say fog.

Also:

• ομίχλη is a feminine noun
• so its singular nominative article is η

That is why you get:

• η ομίχλη = the fog

Literally, φεύγει means leaves / goes away.

So:

• η ομίχλη δεν φεύγει = the fog isn’t going away

In natural English, you might also translate this as:

• the fog isn’t lifting
• the fog isn’t clearing

Greek often uses φεύγω in situations where English might prefer go away, clear, or lift, especially for things like fog, pain, symptoms, and bad weather.

This is a very important Greek-English difference.

Greek often uses the present tense for something that:

• started in the past
• is still continuing now

That is exactly what happens here:

• η ομίχλη δεν φεύγει από το πρωί

Literally: the fog isn’t going away since morning

But natural English usually prefers the present perfect or present perfect progressive:

• the fog hasn’t gone away since this morning
• the fog has been hanging around since this morning

So the Greek present tense here expresses an ongoing situation continuing up to now.

In this sentence, από το πρωί means since the morning / since this morning / since early this morning.

Although από often means from, with time expressions it can also mean since.

So:

• από το πρωί = since this morning
• από χτες = since yesterday
• από τις πέντε = since five o’clock

That is why the phrase sounds natural in Greek even though a word-for-word English translation would sound awkward.

Yes, in this sentence γιατί can be replaced by επειδή.

So you could also say:

• Μπορεί να βρέξει αργότερα, επειδή η ομίχλη δεν φεύγει από το πρωί.

Both mean because here.

A useful thing to remember is:

• γιατί can mean because or why, depending on context
• επειδή means because

Many learners find επειδή easier because it is unambiguous, but γιατί is extremely common in everyday Greek.

The sentence is natural as it stands, but Greek word order is more flexible than English.

The basic version is:

• Μπορεί να βρέξει αργότερα, γιατί η ομίχλη δεν φεύγει από το πρωί.

But you could move some parts for emphasis, for example:

• Η ομίχλη δεν φεύγει από το πρωί, γι’ αυτό μπορεί να βρέξει αργότερα.

That changes the structure a bit, but the idea is similar.

What is less flexible is the internal grammar of chunks like:

• μπορεί να βρέξει
• δεν φεύγει
• από το πρωί

So Greek allows movement, but not completely freely.

Yes. In Greek, a comma is commonly used before a subordinate clause introduced by γιατί when it means because.

So:

• Μπορεί να βρέξει αργότερα, γιατί η ομίχλη δεν φεύγει από το πρωί.

This punctuation is normal and helps separate the main statement from the reason.

In informal writing, punctuation may vary a little, but the comma here is standard.