Learn Hardcore Portuguese (Brazil): Quando faz frio, eu uso um casaco grosso.

Literally, fazer means to make / to do, but here it doesn’t really keep its literal meaning; it’s just part of a fixed pattern for talking about weather.

Using é frio or está frio is possible in some contexts, but:

Faz frio. → neutral, very common for stating the weather.
Está frio. → also common, especially when you mean the air / the temperature is cold right now.
É frio. → usually describes something’s inherent characteristic:
- O inverno aqui é frio. = The winter here is cold. (not warm by nature)

So in your sentence, Quando faz frio... is a natural, standard way to say “When it’s cold…” in general.

What does faz literally mean in faz frio?

Faz is the 3rd person singular of fazer (to do / to make):

eu faço – I do / make
você/ele/ela faz – you/he/she does / makes
nós fazemos – we do / make
etc.

In faz frio, the verb has become impersonal: there is no real subject. We don’t think of it as “it makes cold” in everyday use; we just learn it as the idiomatic way to talk about the weather, similar to English “it’s raining / it’s cold” with a dummy it.

Why isn’t there a word for “it” before faz frio?

Portuguese does not use a dummy subject like English “it” in weather expressions. Instead:

Faz frio. (literally “makes cold”) = It’s cold.
Chove. = It’s raining. (there’s no “it”)
Nevou ontem. = It snowed yesterday.

The verb itself (especially in 3rd person singular) is enough. So you never say “ele faz frio” to mean “it’s cold”. You just say Faz frio.

Is frio here an adjective or a noun, and why is it masculine?

In faz frio, frio behaves like a noun meaning cold / coldness:

Faz frio. = There is cold / It’s cold.
Faz calor. = There is heat / It’s hot.

Because frio is a masculine noun (o frio), it appears in the masculine form. You’ll see it clearly as a noun in phrases like:

Eu não gosto do frio. = I don’t like the cold.

When frio directly describes something, it is an adjective and agrees with the noun:

água fria = cold water (feminine)
vento frio = cold wind (masculine)

So in your sentence, frio is functioning as a masculine noun in a fixed weather expression.

Can I say Quando está frio instead of Quando faz frio? Is there a difference?

Yes, you can say Quando está frio and it’s perfectly correct.

Nuance (not a hard rule, just a tendency):

Quando faz frio...
- Very common, sounds like a general statement about the weather.
- Slightly more “formulaic” as a weather phrase.
Quando está frio...
- Focusing a bit more on the current state/feeling of the air/temperature.
- Still very common and natural.

In many everyday situations, they’re interchangeable:

Quando faz frio, eu uso um casaco grosso.
Quando está frio, eu uso um casaco grosso.

Both sound fine in Brazilian Portuguese.

Why is there a comma after Quando faz frio? Could I leave it out?

In Portuguese, when a dependent clause comes before the main clause, a comma is normally required:

Quando faz frio, eu uso um casaco grosso.
- Dependent clause: Quando faz frio
- Main clause: eu uso um casaco grosso

If you switch the order, the comma is usually not used:

Eu uso um casaco grosso quando faz frio.

So in your original sentence, the comma is correct and expected. In informal writing, some people omit it, but that’s considered a punctuation mistake in standard grammar.

Is the subject pronoun eu necessary here? Could I just say Quando faz frio, uso um casaco grosso?

You can absolutely drop eu:

Quando faz frio, uso um casaco grosso.

Portuguese is a pro-drop language: the verb ending often makes the subject clear, so pronouns like eu, ele, nós can be omitted, especially when context makes it obvious.

Using eu is also fine; it can add clarity or emphasis:

Quando faz frio, eu uso um casaco grosso.
(emphasizing that I do this, as opposed to someone else)

Both versions are grammatically correct and natural.

Why use uso and not a verb like visto? What’s the difference?

usar = to use / to wear
- Eu uso um casaco grosso. = I wear a thick coat.
vestir = to dress / to put on (clothes), or to dress someone
- Eu visto um casaco grosso. = I put on a thick coat.
- Ela veste o filho. = She dresses her son.

Key idea:

usar talks about wearing something as a habit or state.
vestir often suggests the action of putting something on.

In your sentence, you’re describing a habit (“when it’s cold, I (tend to) wear a thick coat”), so uso is the most natural choice.

What exactly does casaco mean? Is it the same as jacket or coat in English?

Casaco is a broad term for something you wear over your clothes to keep warm—it covers both jacket and coat depending on context.

Some related words:

casaco – generic: coat/jacket; can be lighter or heavier.
jaqueta – usually shorter, more casual (like a jacket, bomber, denim).
sobretudo – long overcoat, heavier and more formal.
paletó – suit jacket/blazer (more formal, part of a suit).

In um casaco grosso, you’d usually picture a warm coat/jacket suited for cold weather.

What does grosso mean here? How is it different from quente, pesado or espesso?

Grosso literally means thick. In the context of clothes:

um casaco grosso = a thick (well-padded) coat.

Related adjectives:

quente – warm/hot (describes temperature or how warm something keeps you)
- um casaco quente = a warm coat.
pesado – heavy (physically heavy) or “heavy” in feeling
- um casaco pesado = a heavy coat (in weight).
espesso – thick, but used more for materials (liquids, layers, etc.), less usual for clothes.

You can combine them:

um casaco grosso e quente = a thick, warm coat.

Why is it um casaco grosso and not grosso casaco? Can adjectives come before the noun?

In Portuguese, the default position for adjectives is after the noun:

um casaco grosso = a thick coat
uma casa grande = a big house

Adjectives can come before the noun, but:

It’s less common in everyday speech.
It often adds emphasis or changes the nuance (more subjective, emotional, or stylistic).

For this neutral, descriptive sentence, casaco grosso (noun + adjective) is the normal and most natural order.

Why is there um before casaco? Could I just say Quando faz frio, eu uso casaco grosso?

Here, um is the indefinite article (a / one):

um casaco grosso = a thick coat.

Saying just uso casaco grosso is possible colloquially, but it sounds a bit clipped or stylistically marked. In neutral, standard speech, you’d typically include the article:

Quando faz frio, eu uso um casaco grosso.

Compare:

Eu comprei casaco. (colloquial, “I bought a coat.”)
Eu comprei um casaco. (standard, more natural in most situations)

So in your sentence, um is the normal, idiomatic choice.

How would I say “When it’s very cold, I wear a really thick coat”?

You can intensify both frio and grosso:

Quando faz muito frio, eu uso um casaco bem grosso.

Other natural options:

Quando faz muito frio, eu uso um casaco bem quente.
Quando faz muito frio, eu uso um casaco bem grosso e quente.

Here:

muito = very
bem (before adjectives, in informal speech) = really / very

Does the verb tense faz / uso here express a habit? How would I talk about a specific future situation?

Yes. Using the present indicative in both clauses expresses a general habit or usual behavior:

Quando faz frio, eu uso um casaco grosso.
= Whenever it’s cold, I (typically) wear a thick coat.

For a specific future situation, Brazilians often use the future subjunctive after quando, and a future construction in the main clause:

Quando fizer frio, vou usar um casaco grosso.
= When it gets cold (on that future occasion), I’ll wear a thick coat.

So:

Quando faz frio, eu uso... → general habit, timeless.
Quando fizer frio, vou usar... → specific or future-oriented situation.

Any tips on pronouncing Quando faz frio, eu uso um casaco grosso like a Brazilian?

Key points:

Quando → QUAN-do
- quan has a nasal sound (like “kwan” with the air going through the nose).
faz → sounds like fahs (final z sound is usually like a soft s in Brazil).
frio → FREE-oh (often almost “FREE-u” in quick speech).
eu → roughly “eh-oo” merged into one syllable (“êw”).
uso → OO-zo (Brazilian s between vowels = z sound).
um → nasal “oon”, with air through the nose, lips slightly rounded.
casaco → ca-ZA-co (stress on the middle syllable, s between vowels = z).
grosso → GRO-so (“gro” like in “grow” but shorter, ss sound).

Spoken fast, it might sound like:

QUAN-do fahs FREE-u, êw OO-zo oon ca-ZA-co GRO-so.