Learn Hardcore Portuguese (Brazil): Hoje o céu está azul e as árvores estão bem verdes. - Today the sky is blue and the trees are very green.

Hoje o céu está azul – The sky is blue today, but it might be gray tomorrow. It’s a current, possibly temporary state.
As árvores estão bem verdes – The trees are very green right now, maybe because it’s spring or they were recently watered.

If you said O céu é azul, it would sound more like a general truth (“The sky is blue [as a fact]”), not about how it looks today. Similarly, As árvores são verdes sounds like “Trees are green (as a characteristic of that type of tree)”, not about today’s appearance.

Why is it está in the first part and estão in the second part?

The verb estar has to agree with the subject:

o céu (the sky) – singular → está
as árvores (the trees) – plural → estão

So:

Hoje o céu está azul – The sky is blue today.
… e as árvores estão bem verdes – and the trees are very green.

You cannot say as árvores está or o céu estão; that would be incorrect agreement.

Why do we say o céu and as árvores? Could we drop the articles and just say céu or árvores?

In Portuguese, definite articles (o, a, os, as) are used much more often than in English.

o céu = the sky
as árvores = the trees

Saying Hoje céu está azul is wrong; you need the article: Hoje o céu está azul.
Saying … e árvores estão bem verdes is also wrong; it should be e as árvores estão bem verdes.

You could sometimes drop the article in titles, headlines, or poetic language, but in normal speech and writing, you say o céu, a árvore, as árvores, etc.

What does bem mean in as árvores estão bem verdes? Is it the same bem as in “I am well”?

Yes, it’s the same word bem, but used in a different way.

As an adverb of intensity (like very, really):
- As árvores estão bem verdes. → The trees are really/very green.
  Here bem intensifies verdes.
As “well” (opposite of “badly” or “sick”):
- Eu estou bem. → I am well / I’m fine.

In this sentence, bem definitely means very / really, not well in the health sense. You could replace it with muito (muito verdes) with a similar meaning, although bem verdes is a bit more colloquial and can sound slightly more emphatic.

Why is it verdes (with an s) but azul has no s?

Adjectives in Portuguese agree in number (singular/plural) and often in gender with the noun they describe.

o céu – masculine singular
- Adjective: azul (singular) → O céu está azul.
as árvores – feminine plural
- Adjective: verde in the plural becomes verdes → As árvores estão bem verdes.

So:

Singular: verde
Plural: verdes

We don’t see the plural of azul here because céu is singular. The plural of azul would be azuis:

Os céus estão azuis. – The skies are blue.

Can I move hoje to another position, like O céu hoje está azul or O céu está azul hoje?

Yes, you can move hoje, and all of these are acceptable (with slightly different emphasis):

Hoje o céu está azul e as árvores estão bem verdes.
Neutral, very natural: focus on “today”.
O céu hoje está azul e as árvores estão bem verdes.
Emphasizes “today” as a contrast: the sky today (unlike other days) is blue.
O céu está azul hoje e as árvores estão bem verdes.
Similar meaning; hoje emphasizes “today” as the time frame.

All are correct in Brazilian Portuguese. Position mainly affects nuance, not grammaticality.

Why is bem before verdes? Can I say as árvores estão verdes bem?

Adverbs that intensify adjectives (bem, muito, bem mais, super, etc.) normally come before the adjective:

bem verdes
muito verdes
super verdes

So you say:

As árvores estão bem verdes.

Putting bem after the adjective (verdes bem) is wrong here. The normal pattern is:

estar + adverb of intensity + adjective
→ estão bem verdes

Could I leave out the second estão, like in English “The sky is blue and the trees very green”?

In natural Portuguese, you normally repeat the verb:

Hoje o céu está azul e as árvores estão bem verdes.

If you omit the second estão:

Hoje o céu está azul e as árvores bem verdes.

this might appear in very informal speech or poetic style, but it sounds incomplete or odd in standard usage. In everyday Brazilian Portuguese, you would keep estão in the second part.

How do you pronounce céu and why does it have an accent?

céu has:

c as in s in sell (before e/i, c sounds like s in Portuguese)
é is an open e (like in bet), and the acute accent shows both the stress and the open quality.
u combines with é to form a diphthong éu, similar to “eh-oo” said quickly together.

Pronunciation (Brazilian Portuguese): roughly [sɛw] (like “seh-oo” sliding into one syllable).
The accent marks the stressed syllable and distinguishes it from other words (e.g. without accent it would follow different stress rules).

How do you pronounce árvores, and where is the stress?

árvores is the plural of árvore (tree). Breakdown:

ár – stressed syllable (because of the acute accent)
vo – like “vo” in “vote” but shorter
res – sounds like “rees” or “ris” depending on accent, with a very soft r and usually a weak final vowel sound

Approximate Brazilian pronunciation: [ˈaɾ.vo.ɾis]
Stress is on the first syllable: ÁR-vo-res. The accent on á shows that stress.

Could bem verde mean “unripe” (like for fruit)? Does bem verde always just mean “very green”?

Context is crucial. In many contexts:

bem verde = very/really green

But with certain nouns, especially fruits or vegetables, verde can mean:

verde = unripe
bem verde = very unripe / really not ripe yet

Examples:

A banana ainda está verde. – The banana is still unripe.
A banana está bem verde. – The banana is really unripe.

In your sentence, as árvores estão bem verdes, we are clearly talking about color, not ripeness, because árvores (trees) are naturally green and “unripe trees” is not a usual concept. So here it just intensifies the color.

When would I say as árvores são verdes instead of as árvores estão verdes?

As árvores são verdes.
States a general characteristic, like describing the kind of trees, in a timeless way. It sounds like a simple fact about them: These trees are (the kind that are) green.
As árvores estão verdes.
Focuses on their current state, often compared to another time: they might be greener now than before, or greener than usual, or you are just describing how they look today.

Because the sentence starts with Hoje (Today), the temporary/current-state reading with estar is the natural and correct choice:

Hoje o céu está azul e as árvores estão bem verdes. ✅