Kamo ćemo ako počne kiša?

Kamo means to where? / where to? and is used when there is movement toward a destination.

• Kamo ćemo...? = Where will we go?
• Gdje smo? = Where are we?

So the difference is:

• kamo → direction, destination
• gdje → location, place

In this sentence, kamo is used because the idea is going somewhere if it starts raining.

Ćemo is the 1st person plural form of the auxiliary htjeti used to make the future tense.

• mi ćemo = we will

So:

• Kamo ćemo...? = Where will we...?

In Croatian, the future is often made with:

• a form of htjeti in the present
• plus the infinitive of the main verb

For example:

• Ići ćemo. = We will go.

But in your sentence, the main verb ići is not stated directly, because it is understood from kamo ćemo.

Nothing is missing in a wrong way; it is just understood.

Kamo ćemo? naturally means Where will we go?, even without saying ići.

Croatian often leaves out a verb when it is obvious from context. Here, kamo already strongly suggests movement, so ići is easy to understand.

A fuller version would be:

• Kamo ćemo ići ako počne kiša?

But the shorter version:

• Kamo ćemo ako počne kiša?

sounds very natural.

After ako meaning if, Croatian normally uses the present tense, even when English uses future meaning.

So Croatian says:

• ako počne kiša = literally if rain starts

not:

• ako će početi kiša ❌

This is similar to English in a way:

• If it rains, we’ll go inside.
• not If it will rain... in standard usage

So in Croatian, future meaning after ako is usually expressed with a present-tense form.

Počne is the 3rd person singular present form of the verb početi = to begin / to start.

So:

• počne = begins / starts

In this sentence:

• ako počne kiša = literally if the rain starts

A very important point: početi is a perfective verb. In Croatian, perfective verbs in the present often refer to a future completed event, especially in clauses like this.

So počne here does not mean a habitual present like it starts in general; it means something like:

• if it starts
• if it begins

Croatian word order is more flexible than English word order.

Both of these are possible:

• ako kiša počne
• ako počne kiša

But ako počne kiša sounds very natural. Putting the verb first can make the event feel a bit more immediate or natural in this kind of sentence.

Also, in Croatian, subjects often come after the verb, especially when introducing an event:

• Došao je autobus. = The bus arrived.
• Počinje kiša. = It’s starting to rain / The rain is starting.

So počne kiša is a normal Croatian pattern.

Croatian often expresses weather more directly with a noun or verb, rather than using a dummy subject like English it.

English says:

• if it starts raining

Croatian can say:

• ako počne kiša = literally if rain starts
• ako počne padati kiša = if it starts raining
• ako počne kišiti = if it starts raining (less common in some contexts/styles)

English needs it as a grammatical subject, but Croatian does not use a meaningless subject in the same way.

You might hear it in casual speech, but kamo is the better and more precise choice here.

• Kamo ćemo...? = Where shall we go? / Where to?
• Gdje ćemo...? can sometimes be used colloquially, but literally it is more like Where will we be? or Where are we going to be?

Since the sentence is about movement to a place, kamo is the standard choice.

You could, but it changes the meaning slightly.

• kamo = to what destination?
• kuda = which way? / along what route?

So:

• Kamo ćemo ako počne kiša? = Where will we go if it starts raining?
• Kuda ćemo ako počne kiša? = Which way will we go if it starts raining?

In your sentence, the speaker probably wants a destination, not a route, so kamo is the right word.

Yes. Ćemo is a clitic, and Croatian clitics usually go in the second position of the clause.

So:

• Kamo ćemo ako počne kiša?

Here, ćemo comes right after the first element kamo.

This is a very common Croatian pattern. You will also see things like:

• Sutra ćemo ići.
• Tamo smo bili.
• Kad ćemo krenuti?

Clitic placement is an important part of sounding natural in Croatian.

Croatian has no articles like English a/an/the.

So kiša can mean:

• rain
• the rain

The exact meaning depends on context.

In ako počne kiša, English usually translates it naturally as:

• if it starts raining or
• if the rain starts

But Croatian does not need a separate word for the.

Yes, in normal use it refers to a future situation.

• Kamo ćemo... clearly points to the future: Where will we go...?
• ako počne kiša also refers to a possible future event: if it starts raining

So the whole sentence is about making a plan for what to do later, if rain begins.

A helpful breakdown is:

• Kamo = where to
• ćemo = we will
• ako = if
• počne = starts / begins
• kiša = rain

So a fairly literal version is:

• Where to will we [go] if rain starts?

A natural English translation is:

• Where will we go if it starts raining?