Si fa vent, la meva filla porta una jaqueta i no una camisa.

Because fa vent is the normal everyday expression in Catalan for weather.

• fa literally means it makes / it does
• vent means wind

So fa vent literally looks like it makes wind, but idiomatically it means it’s windy.

You can say és ventós / ventosa in some contexts, but that is more descriptive and less common for ordinary weather talk. A learner should remember:

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

After si meaning if, Catalan normally uses the present indicative for real or possible conditions, just like in many English sentences:

• Si fa vent, ... = If it’s windy, ...

Even if the meaning is about the future, Catalan still usually keeps the present after si:

• Si demà plou, ens quedarem a casa = If it rains tomorrow, we’ll stay home

So si farà vent would sound unnatural in this kind of sentence.

In Catalan, possessives are very often used with a definite article:

• la meva filla = my daughter
• el meu pare = my father
• la seva casa = his/her house

This is one of the big differences from English. English says my daughter, but Catalan usually says the my daughter structurally.

However, the article is often omitted with some family nouns in certain contexts, especially in direct address or very close family references, but for learners, la meva filla is the safest and most standard form here.

Yes. In Catalan, portar can mean:

• to carry
• to bring
• to wear

In this sentence, it means to wear:

• La meva filla porta una jaqueta = My daughter wears / is wearing a jacket

Catalan often uses portar where English uses wear.

Examples:

• Porto ulleres = I wear glasses
• Porta un abric negre = He/She is wearing a black coat

Because Catalan often drops subject pronouns when the verb already shows who the subject is.

Here, porta is the third person singular form, and the subject la meva filla is already stated, so adding ella would usually be unnecessary:

• La meva filla porta una jaqueta = normal
• La meva filla ella porta una jaqueta = unnecessary in normal usage

Catalan works like Spanish or Italian in this way more than English does.

Catalan can omit repeated words when the meaning is clear. This is called ellipsis.

So:

• porta una jaqueta i no una camisa

means:

• wears a jacket and not a shirt
• understood fully as wears a jacket and does not wear a shirt

The second porta is omitted because it would be repetitive. Both versions are possible, but the shorter version is very natural.

Here no contrasts two choices:

• una jaqueta = a jacket
• no una camisa = not a shirt

So it means something like:

• a jacket, not a shirt
• a jacket rather than a shirt

It is not just simple sentence negation; it is being used contrastively to correct or exclude another option.

Because Catalan, like English, often uses the indefinite article when talking about one non-specific item:

• una jaqueta = a jacket
• una camisa = a shirt

The sentence is not referring to a particular known jacket or shirt, so una is appropriate.

Also note the gender:

• jaqueta is feminine → una jaqueta
• camisa is feminine → una camisa

It can correspond to either one depending on context.

Catalan present tense often covers both:

• habitual meaning: wears
• current meaning: is wearing

So:

• La meva filla porta una jaqueta

could mean:

• My daughter wears a jacket
  or
• My daughter is wearing a jacket

In this sentence, because of Si fa vent (If it’s windy), the meaning is probably habitual or general:

• If it’s windy, my daughter wears a jacket and not a shirt

The structure is:

• Si fa vent = if it’s windy
• la meva filla = my daughter
• porta una jaqueta = wears a jacket
• i no una camisa = and not a shirt

So the overall order is:

conditional clause + subject + verb + object + contrast

This is very normal Catalan word order. Nothing unusual is happening except that the second porta is omitted because it is understood.

Yes. Camisa usually means shirt, and the contrast is natural if the speaker wants to say that in windy weather the daughter puts on something warmer or more suitable.

So the idea is:

• when it’s windy, she wears a jacket
• not a shirt

Even if English might sometimes prefer instead of just a shirt, the Catalan sentence is straightforward and natural.