Nonostante il cielo sereno, stasera potrebbe piovere.

Nonostante means despite or in spite of.

In this sentence, nonostante il cielo sereno means despite the clear sky.

A useful thing to know is that nonostante can be followed by:

• a noun phrase: nonostante la pioggia = despite the rain
• a pronoun: nonostante tutto = despite everything
• even a clause in more advanced usage: nonostante fosse tardi = although it was late

Here it is followed by the noun phrase il cielo sereno.

Because after nonostante, Italian often uses a noun phrase, not a full sentence.

So:

• nonostante il cielo sereno = despite the clear sky

instead of:

• nonostante il cielo è sereno ❌

If you want a full clause, Italian would normally restructure it, for example:

• anche se il cielo è sereno = even though the sky is clear
• benché il cielo sia sereno = although the sky is clear

So in your sentence, il cielo sereno works like a compact expression: the clear sky.

Because sereno agrees with cielo, and cielo is a masculine singular noun.

So:

• il cielo sereno = the clear sky

Agreement in Italian works like this:

• masculine singular: sereno
• feminine singular: serena
• masculine plural: sereni
• feminine plural: serene

Examples:

• la notte serena = the clear/calm night
• i giorni sereni = the clear days

Here sereno means clear, as in without clouds.

With weather, cielo sereno is a very common expression meaning:

• clear sky
• cloudless sky

But sereno can also have other meanings depending on context, such as:

• calm
• peaceful
• serene

For example:

• sembra sereno = he/she seems calm
• una serata serena = a peaceful evening

So in this sentence, the weather meaning is the important one.

Yes, stasera and questa sera both mean tonight / this evening.

• stasera is a very common, compact form
• questa sera is slightly more explicit, but both are natural

So these are both fine:

• Stasera potrebbe piovere
• Questa sera potrebbe piovere

In everyday speech, stasera is extremely common.

Potrebbe is from the verb potere = to be able to / can / may / might.

Here potrebbe piovere means:

• it might rain
• it could rain

Grammatically, potrebbe is the:

• third person singular
• conditional present

of potere.

A quick comparison:

• può piovere = it can/may rain
• potrebbe piovere = it could/might rain

The conditional makes the statement sound less certain and more tentative.

Because the sentence expresses possibility, not certainty.

Compare:

• stasera pioverà = it will rain tonight
  → sounds more definite
• stasera potrebbe piovere = it might rain tonight
  → sounds uncertain, just a possibility

So potrebbe is chosen because the speaker is not sure. That fits well with nonostante il cielo sereno: even though the sky is clear now, rain is still possible later.

Because in Italian, weather verbs like piovere are usually used without an expressed subject.

English says:

• it might rain

But Italian simply says:

• potrebbe piovere

There is no real subject word here. This is normal with weather expressions such as:

• piove = it is raining
• nevica = it is snowing
• grandina = it is hailing

Italian does not need a dummy subject like English it.

Because after a conjugated form of potere, Italian normally uses an infinitive.

So:

• potrebbe piovere = might rain
• può venire = he/she can come
• potremmo uscire = we could go out

The pattern is:

• potere + infinitive

Here:

• potrebbe = might/could
• piovere = rain

Together: might rain.

The comma separates the introductory phrase from the main clause:

• Nonostante il cielo sereno, = introductory contrast
• stasera potrebbe piovere. = main statement

This makes the sentence easier to read and highlights the contrast:

• clear sky now
• possible rain later

In short, the comma is natural and helpful here, though punctuation can sometimes vary depending on style.

Yes. Italian word order is flexible, although some versions sound more natural in context than others.

The original sentence:

• Nonostante il cielo sereno, stasera potrebbe piovere.

Possible alternatives:

• Stasera, nonostante il cielo sereno, potrebbe piovere.
• Potrebbe piovere stasera, nonostante il cielo sereno.

These all make sense, but the original version is very natural because it sets up the contrast first: despite the clear sky...

Yes, depending on the structure you want.

Common alternatives include:

• malgrado = despite
• anche se = even if / even though
• sebbene = although
• benché = although

Examples:

• Malgrado il cielo sereno, stasera potrebbe piovere.
• Anche se il cielo è sereno, stasera potrebbe piovere.
• Sebbene il cielo sia sereno, stasera potrebbe piovere.

Notice the difference:

• nonostante / malgrado are often followed by a noun phrase
• anche se / sebbene / benché are followed by a full clause

Also, sebbene and benché usually require the subjunctive, which makes them a bit more advanced.