Llevo una chaqueta extra por si hace frío esta noche.

Yes — llevo comes from llevar, which often means to carry, to take, or to wear/have on depending on context.

In this sentence, llevo una chaqueta extra means something like:

• I’m taking an extra jacket
• I’m bringing an extra jacket
• possibly I have an extra jacket with me

Spanish uses llevar more broadly than English uses carry. So even if you are not physically holding it in your hands, llevar can still be the natural verb.

That is a very common question. Both llevar and traer can relate to bringing/taking, but the difference depends on direction.

• llevar = to take/carry something away from the speaker’s reference point
• traer = to bring something toward the speaker’s reference point

In this sentence, the speaker is simply saying they are taking an extra jacket along, not emphasizing bringing it here to where someone is. So llevo sounds natural.

If the situation were different, traigo might be possible, but llevo una chaqueta extra is the standard choice for I’m taking an extra jacket with me.

Por si means in case.

So:

• por si hace frío = in case it gets cold / in case it’s cold

A very important point: after por si, Spanish normally uses the indicative, not the subjunctive.

Examples:

• Lleva dinero por si necesitas un taxi. = Take some money in case you need a taxi.
• Te llamo por si estás en casa. = I’ll call in case you’re at home.

So por si hace frío is correct, not por si haga frío.

In Spanish, weather expressions often use hacer:

• hace calor = it’s hot
• hace frío = it’s cold
• hace viento = it’s windy

So hace frío is the normal way to say it’s cold in the sense of weather or temperature.

Es frío would usually describe a person, thing, or place as cold in a more general descriptive sense, not the weather expression used here.

Because frío here is part of the fixed expression hacer frío. It works like a noun in this weather structure:

• hace frío
• hace calor

You do not normally pluralise it in this kind of sentence.

In standard Spanish, esta noche is the normal way to say tonight.

• esta noche = tonight / this evening-tonight

Hoy por la noche can also be used and means tonight as well, but esta noche is shorter and very natural.

For a learner of Spanish from Spain, esta noche is the most straightforward everyday expression.

Yes, extra is an adjective here, meaning additional or spare.

So:

• una chaqueta extra = an extra jacket / an additional jacket

In Spanish, extra often comes after the noun:

• dinero extra = extra money
• tiempo extra = extra time
• una manta extra = an extra blanket

That post-noun position is very common.

Yes, you could, but it is not always exactly the same in tone.

• una chaqueta extra = an extra jacket / an additional jacket
• una chaqueta de más = one jacket too many / an extra jacket beyond what is necessary

Extra sounds neutral and very natural here.
De más can sometimes suggest more than needed, depending on context.

So in this sentence, una chaqueta extra is the better choice.

Because hacer frío is a fixed weather expression. Spanish does not say hace el frío here.

Just as you say:

• hace calor
• hace sol
• hace buen tiempo

you also say:

• hace frío

No article is needed.

Spanish often uses the present tense to talk about future situations when the time reference is clear.

Here, esta noche already tells you the time, so:

• por si hace frío esta noche

means:

• in case it gets cold tonight
• in case it’s cold tonight

English often uses a future idea here, but Spanish naturally uses the present.

Normally, no. Por si hará frío sounds unnatural here.

Spanish usually uses the present indicative after por si:

• por si hace frío
• por si llueve
• por si no viene

So even though the event is in the future, the present tense is the normal choice.

Because por si normally takes the indicative, not the subjunctive.

This is one of those places where English speakers often expect uncertainty to trigger the subjunctive, but Spanish does not usually do that after por si.

So:

• Correct: por si hace frío
• Not standard here: por si haga frío

Think of por si as introducing a possible situation that is being treated as a real possibility, so the indicative is used.

Yes, chaqueta is a very common and natural word for jacket in Spain.

Depending on the type of clothing, you might also hear:

• abrigo = coat
• cazadora = jacket, often a casual or shorter jacket
• americana = blazer / suit jacket

But for a general jacket, chaqueta is a very safe and common choice.

Potentially, yes — llevar can mean to wear. But in this sentence, because of the context por si hace frío esta noche, the most natural interpretation is:

• I’m taking an extra jacket
• I’m bringing an extra jacket along

If the sentence were just Llevo una chaqueta, it could mean I’m wearing a jacket.
Adding extra makes the idea of an additional jacket more likely.

To some extent, yes. The given sentence is very natural:

• Llevo una chaqueta extra por si hace frío esta noche.

You could also hear:

• Por si hace frío esta noche, llevo una chaqueta extra.

That version puts more emphasis on the reason first: In case it gets cold tonight, I’m taking an extra jacket.

Both are correct, but the original order sounds very normal in everyday speech.

Yes, me llevo una chaqueta extra is possible and often means I’m taking an extra jacket with me.

Compared with plain llevo, me llevo can sound a bit more explicitly like you are taking it along for yourself.

So:

• Llevo una chaqueta extra = I’m taking an extra jacket
• Me llevo una chaqueta extra = I’m taking an extra jacket with me

Both are natural. The version without me is perfectly fine.

A few very natural translations would be:

• I’m taking an extra jacket in case it gets cold tonight.
• I’m bringing an extra jacket in case it’s cold tonight.
• I’ve got an extra jacket with me in case it gets cold tonight.

The exact English version depends on context, but the Spanish sentence itself is very natural and idiomatic.