Avui fa sol i no fa fred.

Here fa is the 3rd person singular of fer, which usually means to do or to make.

But in weather expressions, Catalan very often uses fer in a special idiomatic way:

• fa sol = it’s sunny
• fa fred = it’s cold
• fa calor = it’s hot
• fa vent = it’s windy

So in this sentence, fa does not mean does in the usual sense. It is just the normal verb Catalan uses in many weather expressions.

Because Catalan commonly describes weather with fer.

This pattern is very productive, so learners quickly see it again and again:

• fa bon temps = the weather is nice
• fa mal temps = the weather is bad
• fa fresca = it’s cool
• fa xafogor = it’s muggy

So fa sol and fa fred are both standard weather phrases. English uses different structures such as it’s sunny and it’s cold, but Catalan often uses the same verb for both.

Because Catalan does not need a dummy subject the way English does.

English says:

• It is cold
• It is sunny

But that it does not really refer to anything. It is just there because English grammar requires a subject.

Catalan usually omits that kind of empty subject, so you simply say:

• fa fred
• fa sol

That is completely normal.

In Catalan, the basic negative particle no goes before the verb:

• fa fred = it’s cold
• no fa fred = it isn’t cold

This is the normal way to make a sentence negative.

So the structure is:

• no + verb

Examples:

• No plou = It isn’t raining
• No tinc temps = I don’t have time
• No és fàcil = It isn’t easy

Because these are fixed weather expressions, and they normally appear without an article.

So you say:

• fa sol
• fa fred
• fa calor

not usually:

• fa el sol
• fa el fred

In these expressions, Catalan treats them as part of an established pattern rather than as ordinary noun phrases.

In fa fred, fred behaves more like a noun-like weather expression than like a normal adjective.

Compare:

• L’aigua és freda = The water is cold
  Here freda is clearly an adjective agreeing with aigua.

But:

• Fa fred = It’s cold
  Here fred is part of the idiomatic weather structure with fer.

So even though fred can be an adjective in other contexts, in fa fred you should learn it as a complete expression.

Usually, for general weather, fa fred is the natural choice.

• Fa fred = It’s cold out / The weather is cold

By contrast:

• està fred usually means something is cold in its current state
  
  • El cafè està fred = The coffee is cold
• és fred usually describes something as cold by nature or character
  
  • És una persona freda = He/She is a cold person

So if you are talking about the weather in general, fa fred is the standard expression.

Avui means today, and putting it first is a very natural way to set the time frame right away:

• Avui fa sol i no fa fred.

This is a neutral and common word order.

Catalan word order is somewhat flexible, so you may also hear:

• Fa sol avui i no fa fred

But starting with avui sounds very natural when the speaker wants to frame the whole sentence with today.

Yes, you may hear hi ha sol, but it is not exactly the same in feel.

• fa sol = the standard weather expression for it’s sunny
• hi ha sol = literally there is sun, which focuses more on the presence of sunshine

So both can be possible depending on context, but for a basic weather statement, fa sol is the most typical phrase to learn first.

Because i simply means and, and it clearly links the two ideas:

• fa sol
• no fa fred

So:

• Avui fa sol i no fa fred.

Using i is the most natural way to join them into one sentence. A comma by itself would feel less complete in standard writing.

A simple learner-friendly pronunciation is:

ah-VWEE fah SOL ee no fah FRET

A few helpful notes:

• avui sounds roughly like ah-VWEE
• fa is short: fah
• sol is like sole without the strong English diphthong
• i is just ee
• fred ends with a clear t-like final sound in many accents, so it may sound close to fret

The exact pronunciation varies by accent, but this is a good approximation for learners.

Yes. You can keep the same structure and just change the time expression:

• Avui fa sol. = Today it’s sunny.
• Demà farà fred. = Tomorrow it will be cold.
• Ahir feia vent. = Yesterday it was windy.

This is useful because once you know the pattern fer + weather expression, you can reuse it very easily in different tenses.