Avui fa vent i fa fred.

Yes, fa is the 3rd person singular of fer, which often means to do or to make. But in Catalan, fer is also used in many weather expressions.

So:

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

This is just the normal Catalan pattern for talking about weather.

Because fa vent and fa fred are two separate weather expressions, and Catalan normally keeps fa with each one.

So Catalan naturally says:

• Avui fa vent i fa fred

That sounds more complete and idiomatic than trying to share one fa across both parts. English often avoids repetition, but Catalan is happy to repeat the verb here.

Catalan does not need a dummy subject like English it in weather sentences.

English says:

• It is cold
• It is windy

But Catalan simply says:

• Fa fred
• Fa vent

There is no real subject, and Catalan does not need to insert one.

Because weather conditions like cold, heat, wind, and sun are commonly expressed with fer in Catalan, not with ser or estar.

So the usual forms are:

• fa fred
• fa calor
• fa vent
• fa sol

Using és or està here would sound unnatural or would change the meaning.

Here they are best understood as part of fixed weather expressions, and both behave like nouns in this structure.

• vent is a noun meaning wind
• fred can be an adjective in other contexts, but in fa fred it works like a noun meaning cold

That is why Catalan says:

• fa vent literally something like it makes wind
• fa fred literally something like it makes cold

Even though English uses adjectives like windy and cold, Catalan often uses these noun-based expressions instead.

Because in these weather expressions, Catalan normally uses the noun without an article.

So you say:

• fa vent
• fa fred

Not:

• fa el vent
• fa el fred

The article would usually make it sound like you are talking about a specific wind or a specific cold, not the general weather condition.

Avui means today. It sets the time for the whole sentence.

So:

• Avui fa vent i fa fred = today, it is windy and cold

Placing avui at the beginning is very natural because it frames the whole statement right away. Catalan word order is fairly flexible, but sentence-initial avui is common and clear.

Yes. If the context already makes the time clear, you can simply say:

• Fa vent i fa fred

That means It’s windy and cold.
Adding avui just makes the time explicit.

Yes, hi ha vent is possible, and it means there is wind. But fa vent is the more typical everyday weather expression.

So:

• fa vent = idiomatic weather expression
• hi ha vent = there is wind, more literal/descriptive

For cold, though, fa fred is the normal expression. Hi ha fred is much less natural in ordinary weather talk.

This is a very important distinction:

• fa fred = the weather is cold
• tinc fred = I am cold

So:

• Avui fa fred = today the weather is cold
• Tinc fred = I feel cold

English uses cold in both cases, but Catalan uses different structures.

You can add words such as molt.

For example:

• Avui fa molt fred = Today it is very cold
• Avui fa molt vent = Today it is very windy / there is a lot of wind

You can also soften it:

• fa una mica de fred = it is a little cold
• fa una mica de vent = it is a little windy

Usually it describes the current weather conditions for today. It sounds like a normal observation about today’s weather.

So Avui fa vent i fa fred most naturally means that today’s weather is windy and cold. It is not usually a timeless general truth; it refers to the day in question.