Si hace buen tiempo, queremos acampar cerca del arroyo este fin de semana.

Spanish usually uses hacer with weather expressions:

• hace buen tiempo = the weather is nice / it’s good weather
• hace mal tiempo = the weather is bad
• hace frío = it’s cold
• hace calor = it’s hot

So hacer is the normal verb here, not ser.

Bueno becomes buen before a singular masculine noun.

• un buen día
• buen tiempo
• un buen libro

Since tiempo is a singular masculine noun, Spanish uses buen here.

In Spanish, real or possible future conditions often use the present tense after si.

So:

• Si hace buen tiempo, queremos acampar.

This literally looks like If the weather is good, we want to camp, but it naturally means If the weather is good, we want / plan / intend to camp.

This is very normal Spanish. Unlike English, you do not use a future tense after si in this kind of sentence.

So Si hará buen tiempo... would be wrong here.

Spanish often uses the present tense to talk about near-future plans, especially when the time is already clear from context.

Here, este fin de semana already tells us the action is in the future, so queremos acampar means something like:

• we want to camp
• we’re planning to camp
• we intend to camp

A future form like querremos is not natural here.

You could also say:

• Si hace buen tiempo, vamos a acampar... = If the weather is good, we’re going to camp...
• Si hace buen tiempo, acamparemos... = If the weather is good, we will camp...

But queremos acampar emphasizes intention or desire.

Literally, it means we want to camp.

In context, though, it often sounds a bit stronger than simple desire and can imply:

• we’d like to camp
• we’re hoping to camp
• we plan to camp, depending on context

So it is about intention, not just a random wish.

Because cerca is normally followed by de:

• cerca de la playa
• cerca del río
• cerca de casa

Here:

• de + el = del

So:

• cerca de el arroyo becomes cerca del arroyo

That contraction is required.

Arroyo usually means stream, brook, or small creek.

It is not exactly the same as río:

• río = river
• arroyo = a smaller watercourse, like a stream or creek

Depending on region and context, the exact size can vary a bit, but arroyo is generally smaller than río.

Spanish often places time expressions like this at the end, but the position is flexible.

So these are all possible:

• Si hace buen tiempo, queremos acampar cerca del arroyo este fin de semana.
• Este fin de semana, si hace buen tiempo, queremos acampar cerca del arroyo.
• Si hace buen tiempo este fin de semana, queremos acampar cerca del arroyo.

The original version sounds very natural. Putting este fin de semana at the end keeps the sentence flowing smoothly.

Yes, when the si clause comes first, Spanish normally uses a comma before the main clause:

• Si hace buen tiempo, queremos acampar...

If the order is reversed, the comma is usually not needed:

• Queremos acampar cerca del arroyo este fin de semana si hace buen tiempo.

So the comma in the original sentence is correct.

In standard Spanish, hace buen tiempo is much more natural and idiomatic.

• hace buen tiempo = normal
• hay buen tiempo = much less natural in this context

A native speaker would usually choose hacer for general weather conditions.

Spanish does not need the article here because buen tiempo is part of a fixed weather expression:

• Hace buen tiempo
• Hace mal tiempo

You would not normally say hace el buen tiempo in this meaning.

So the sentence is using the standard expression exactly as it should.

Yes. Acampar is the simple verb to camp, but Spanish also has other natural ways to express the idea:

• queremos acampar = we want to camp
• queremos ir de camping = we want to go camping
• vamos a acampar = we’re going to camp

All are possible, but acampar is direct and very common.

Yes, it sounds perfectly natural in Spain, and it would also be understood across the Spanish-speaking world.

A few notes:

• este fin de semana is very common in Spain.
• arroyo is standard Spanish, though some regions might more often use another word depending on the landscape.
• The overall grammar is general Spanish, not just Spain-specific.

So it works well for Spanish from Spain and also for wider standard usage.