Learn Hardcore Portuguese (Brazil): O céu está claro hoje.

Portuguese uses articles more than English, especially with singular countable nouns like céu. You would only drop the article in certain fixed expressions or titles, not in a normal sentence like this.

What does the accent in céu do, and how do I pronounce it?

The accent in céu is an acute accent (´) over é. It has two main effects:

Stress: It tells you the stressed syllable is céu (it’s a one‑syllable word anyway, but the accent is still written).
Vowel quality: é is an open /ɛ/ sound (like “e” in “bed”), not a closed /e/ (like “ay” in “say”).

Pronunciation (Brazilian Portuguese):

céu ≈ /sɛw/ – kind of like “seh-oo” said quickly in one beat.

It does not rhyme with English “few” or “say”; the vowel is shorter and more open.

Why is it está and not é? What’s the difference here?

Portuguese has two verbs that both translate as to be:

ser → é (he/she/it is) – more permanent / characteristic things
estar → está (he/she/it is) – more temporary / current state things

For the sky:

O céu é azul. = The sky is blue. (a general characteristic)
O céu está claro hoje. = The sky is clear today. (its state right now)

If you said O céu é claro hoje, it would sound strange or wrong, as if you were talking about a permanent property that only applies today.

What exactly does claro mean here? I’ve seen it mean “of course” and “light (color)” too.

Claro is very flexible in Portuguese. Common meanings:

Clear / cloudless / not overcast
- O céu está claro hoje. = The sky is clear today.
Light (color or shade)
- azul-claro = light blue
- Ela tem olhos castanhos claros. = She has light brown eyes.
Bright / well lit
- O quarto está claro. = The room is bright/well lit.
Of course / sure (as a standalone response)
- — Você pode me ajudar?
  — Claro! = Of course! / Sure!

In your sentence, claro = clear (sky) or not cloudy. Other common ways to say that:

O céu está limpo hoje. (literally “clean”, meaning cloudless)
O céu está aberto hoje. (lit. “open”, often “no clouds / no rain”)

Why is it claro and not clara? How does agreement work here?

In Portuguese, adjectives agree in gender and number with the noun they describe.

céu is masculine singular → o céu
So the adjective must also be masculine singular → claro

Examples:

O céu está claro. (masc. sing.)
A água está clara. (fem. sing.)
Os céus estão claros. (masc. plural)
As noites estão claras. (fem. plural)

So you say claro (not clara) because céu is masculine.

Can I change the word order? For example, can I say Hoje o céu está claro?

Yes, you can move hoje around. All of these are natural in Brazilian Portuguese:

O céu está claro hoje. (very common)
Hoje o céu está claro. (also very common, puts a bit more emphasis on today)
O céu hoje está claro. (less common, but possible; emphasizes the sky, then specifies today)

The meaning is the same; you’re just changing what feels slightly more emphasized in speech.

Is hoje necessary? What if I just want to say “The sky is clear” in general?

You don’t have to use hoje if the time is clear from context or if you’re just describing the current situation.

O céu está claro. = The sky is clear. (now / at the moment)

If you want to talk about a general tendency, you usually switch to ser and a different adjective:

Aqui o céu é quase sempre limpo.
Here the sky is almost always clear.

So:

estar + claro → current state (today, now)
ser + (often another adjective) → general characteristic

How do I say “The sky is very clear today” or “The sky isn’t clear today”?

“The sky is very clear today.”
- O céu está muito claro hoje.
muito = very (before adjectives and adverbs).
“The sky isn’t clear today.”
- O céu não está claro hoje.
não usually goes before the verb in Portuguese:
- não está, não é, não gosta, etc.

What form of estar is está? How does this verb conjugate?

Está is the 3rd person singular of estar in the present tense:

eu estou – I am
você / ele / ela está – you (sg.) are / he / she is
a gente está – we are (informal, spoken)
nós estamos – we are
vocês / eles / elas estão – you (pl.) are / they are

In O céu está claro hoje, the subject is o céu (3rd person singular), so we use está.

Why is there no subject pronoun like ele? In English we say “It is clear”.

Portuguese only uses subject pronouns when the subject is actually a pronoun:

Ele está aqui. = He is here.
Ela está aqui. = She is here.

In your sentence, the subject is a noun phrase:

O céu = the sky → O céu está claro hoje.

You do not add ele in front of it:

Ele o céu está claro hoje. ❌ (incorrect)

If you want to replace o céu with a pronoun later, you can use ele:

O céu está claro hoje. Ele está lindo.
The sky is clear today. It/He is beautiful. (Portuguese uses ele, because céu is grammatically masculine.)