Learn Hardcore Portuguese (Brazil): Nas montanhas, o tempo muda rápido e geralmente faz frio à noite. - In the mountains, the weather changes quickly and it is usually cold at night.

Em montanhas without an article is grammatically possible but sounds odd and very unnatural here. It would sound like random mountains, almost like “in mountains” used as a bare, abstract category, which is not how people normally speak.

So you almost always say:

nas montanhas (natural)
Not:
em montanhas (strange in this context)

Why is tempo used for “weather” when it usually means “time”?

In Brazilian Portuguese, tempo has two very common meanings:

time (duration, abstract time)
- Não tenho tempo. = I don’t have time.
weather
- O tempo está bom. = The weather is good.

In this sentence, o tempo clearly means the weather.

There is also the word clima, which can mean climate and sometimes weather, but for day‑to‑day “what’s the weather like?” Brazilians most often say tempo:

Como está o tempo hoje? = How’s the weather today?

Context tells you whether tempo means “time” or “weather.”

Why do we say o tempo (with o) instead of just tempo?

Portuguese uses the definite article (o, a, os, as) more often than English, especially with general or abstract nouns.

O tempo muda rápido.
Literally: The weather changes fast.

If you dropped the o and said Tempo muda rápido, it would sound incomplete or poetic. In neutral, everyday speech, you use o tempo here.

Why is it muda rápido and not muda rapidamente? Are both correct?

Both are grammatically correct:

muda rápido
muda rapidamente

In Brazilian Portuguese, the adjective form (rápido) is very often used as an adverb meaning “quickly / fast.” It’s more common and more natural in everyday speech than rapidamente, which can sound a bit more formal or emphatic.

So:

O tempo muda rápido. = The weather changes fast. (most natural)
O tempo muda rapidamente. = The weather changes quickly. (correct, a bit more formal)

Can rápido come before the verb, like rápido muda?

No, not in this sentence. The normal position for rápido as an adverb is after the verb:

O tempo muda rápido. ✅

Putting it before the verb (rápido muda o tempo) would sound strange or poetic and is not how people normally speak when describing weather.

Why do we say faz frio instead of something like é frio or está frio?

In Portuguese, many weather expressions use the verb fazer in the 3rd person singular, impersonal form:

Faz frio. = It’s cold.
Faz calor. = It’s hot.
Faz sol. = It’s sunny.
Faz vento. = It’s windy.

Literally, fazer means “to make/do”, but here it’s an impersonal construction (no real subject, like English “it rains”).

É frio means “it is cold” as a permanent or characteristic trait (e.g., “Canada is cold”).
Está frio means “it is cold right now” (state at the moment).

In talking about typical conditions at night in the mountains, faz frio à noite sounds very natural and idiomatic.

What’s the difference between faz frio and está frio?

Both can translate as “it’s cold,” but they feel slightly different:

Faz frio.
- Very common and idiomatic for weather.
- Focuses on the external condition: “There is cold (weather).”
Está frio.
- Focuses more on the current state: “It is (feels) cold right now.”

In many everyday situations they can be used interchangeably. In this sentence (describing typical conditions at night in the mountains), faz frio à noite is especially natural because we’re talking about the general weather there.

Why is geralmente placed before faz? Can it go somewhere else?

Geralmente = generally / usually.

Standard and most natural position here:

… o tempo muda rápido e geralmente faz frio à noite.

You can move geralmente, but not all positions sound equally natural:

Geralmente, o tempo muda rápido e faz frio à noite. ✅
O tempo geralmente muda rápido e faz frio à noite. ✅
O tempo muda rápido e faz geralmente frio à noite. 🟡 (possible, but a bit awkward)

Brazilians most often put geralmente near the beginning of the clause or right before the verb phrase, as in the original sentence.

Why does à noite have an accent? What’s the difference between à noite and a noite?

À noite has a grave accent marking crase, which is the fusion of:

preposition a (to/at)
article a (the, feminine singular)

So:

a (prep) + a (article noite) → à noite

À noite usually means at night / in the evening in a general or habitual sense:

Geralmente faz frio à noite. = It’s usually cold at night.

A noite (without accent) can appear in other contexts, for example when a noite is just a noun with an article, with no preposition a before it:

A noite estava silenciosa. = The night was silent.

So:

à noite = at night (time expression with preposition)
a noite = the night (as a noun phrase)

Could we say de noite instead of à noite? Is there a difference?

Yes, you can say de noite, and it is very common in Brazilian Portuguese:

Geralmente faz frio de noite.

In most contexts, à noite and de noite are close in meaning (“at night”), and both are natural.

Nuances (not strict rules):

à noite can sound a bit more formal or neutral.
de noite can sound slightly more colloquial in some regions.

In this sentence, both faz frio à noite and faz frio de noite are correct and natural.

Why is frio in the masculine singular form? Should it agree with anything?

In faz frio, frio is a masculine singular noun/adjective used in an impersonal expression. There’s no explicit noun that it has to agree with.

Faz frio. (literally “It makes cold.”)

Because the construction is impersonal, frio stays in the default masculine singular form. You would only change it (e.g., frias, fria) if it were directly modifying a specific feminine or plural noun:

Noites frias. = cold nights.

Here, it’s not modifying a noun; it’s just describing the weather, so frio stays masculine singular.

How is montanhas pronounced, especially the nh?

Montanhas is pronounced roughly: mon-TA-n(y)as.

mon – like “mon” in “Montreal,” but with a short “o” (like mon in “monitor”)
ta – stressed syllable, like “TAH”
nh – this is a single sound, like the ny in “canyon” or “onion”
as – like “ahs” (unstressed)

So nh in montanhas sounds similar to:

Spanish ñ in montaña
English ny in “canyon”

Full approximate pronunciation: mons-TA-nyas (with a softer final -as).