Learn Hardcore Portuguese (Portugal): A rua principal fica perigosa devido ao nevoeiro. - The main street becomes dangerous due to the fog.

Here, fica is the 3rd person singular of ficar, which can mean to become, to stay, or to be located. In a rua principal fica perigosa, it expresses a change of state: the main street becomes dangerous. Context tells you it’s describing a temporary or situational quality.

Why is it devido ao nevoeiro and not just devido nevoeiro?

The phrase devido a (“due to”) must be followed by an article plus noun. You need:

a (preposition) + o (definite article, masculine) → ao
nevoeiro (noun)

So devido a + o nevoeiro = devido ao nevoeiro. Omitting the article (the “o”) would be ungrammatical.

Can I say por causa do nevoeiro instead of devido ao nevoeiro?

Yes. por causa de (“because of”) is more common in speech and less formal:

A rua principal fica perigosa por causa do nevoeiro.

Both mean roughly the same, though devido a sounds slightly more formal or literary.

Why is principal placed after rua and not before, like in English?

In Portuguese, most descriptive adjectives follow the noun:

noun + adjective → rua principal

Putting principal before (e.g. a principal rua) is possible for emphasis or stylistic reasons, but the normal order is after.

Could I start the sentence with Devido ao nevoeiro? Would that change the meaning?

Yes, you can front the phrase for emphasis:

Devido ao nevoeiro, a rua principal fica perigosa.

Meaning stays the same; starting with the cause shifts focus onto the fog first.

What’s the difference between nevoeiro, névoa, and bruma?

They all refer to fog/mist but vary in intensity and register:

nevoeiro: dense fog near the ground, common everyday term.
névoa: lighter mist or haze.
bruma: poetic or old-fashioned term, often for sea mist or general haze.

How does adjective agreement work with perigosa?

Adjectives in Portuguese agree in gender and number with the noun:

rua is feminine singular → perigosa (feminine singular)
For a masculine noun: perigoso
For plural: add s → ruas perigosas

Why isn’t there a comma before devido ao nevoeiro?

Short adverbial phrases at the end typically don’t need commas in Portuguese. Commas are used for long or parenthetical additions. Here devido ao nevoeiro is a concise complement, so no comma is required.