Ako se poslije kiše otopli, djeca će opet trčati po dvorištu.

Ako means if and introduces a condition:

• Ako se poslije kiše otopli = If it gets warmer after the rain
• djeca će opet trčati po dvorištu = the children will run around the yard again

So the whole sentence is a normal if-clause + result clause structure.

After ako in Croatian, you often do not use a future form the way you would in English. Instead, Croatian commonly uses the present form of a perfective verb to refer to a future event in a condition.

So:

• Ako se otopli = If it gets warmer
• not usually Ako će se otopliti

This is a very important pattern in Croatian:

• Ako dođe, javit ću ti. = If he comes, I’ll let you know.
• Ako padne kiša, ostat ćemo doma. = If it rains, we’ll stay home.

Here se is part of the verb expression otopliti se, which means to get warmer / to warm up.

It is not a separate word you translate literally every time. In many Croatian verbs, se is built into the meaning.

Compare:

• otopliti se = to become warmer
• smijati se = to laugh
• bojati se = to be afraid
• nadati se = to hope

So in this sentence, learn otopliti se as a unit.

Croatian often leaves the subject unstated when it is general or obvious from context.

In this sentence, otopli is used impersonally, like English it gets warmer. But Croatian does not need a dummy subject like English it.

So:

• English: If it gets warmer...
• Croatian: Ako se otopli...

There is no actual word for that English it.

Kiše is in the genitive singular because it comes after poslije.

• kiša = rain
• poslije kiše = after the rain

Many prepositions in Croatian require a specific case, and poslije takes the genitive.

Other examples:

• poslije škole = after school
• poslije ručka = after lunch
• poslije posla = after work

More or less, yes, but with some differences.

• poslije is standard Croatian and very common.
• nakon also means after and is a bit more formal or neutral in style.
• posle is common in Serbian, while Croatian normally uses poslije.

So in Croatian:

• poslije kiše
• nakon kiše

Both are correct. In this sentence, poslije sounds very natural.

Djeca means children, but grammatically it behaves as a neuter singular collective noun in standard Croatian.

That means it often takes singular agreement, especially with past participles and adjectives. But with the future using će + infinitive, you do not see agreement on the verb anyway, because će is the same for all third-person singular/plural forms in this construction.

So:

• djeca će trčati = the children will run

This is just the normal future construction.

A useful thing to remember:

• meaning: plural (children)
• grammar: often treated as singular collective noun

This is the future tense in Croatian.

It is formed with:

• the auxiliary ću, ćeš, će, ćemo, ćete, će
• plus the infinitive

So:

• ja ću trčati = I will run
• ti ćeš trčati = you will run
• on/ona/ono će trčati = he/she/it will run
• djeca će trčati = the children will run

In this sentence:

• će trčati = will run

Opet means again.

Here it shows that the children will resume doing something they were doing before:

• djeca će opet trčati = the children will run again

Its position is flexible, but this placement is very natural:

• djeca će opet trčati po dvorištu

You may also hear other word orders for emphasis, but the sentence as given is standard and natural.

Po dvorištu means something like around the yard / all over the yard.

The preposition po often gives a sense of movement over, around, across, throughout an area.

• trčati po dvorištu = to run around the yard

If you said u dvorištu, that would mean more simply in the yard, focusing on location rather than movement around within the space.

So:

• u dvorištu = in the yard
• po dvorištu = around the yard / all over the yard

Dvorištu is in the locative singular after po.

• dvorište = yard, courtyard
• po dvorištu = around the yard

With meanings like movement around within an area or distribution over a surface/space, po commonly takes the locative.

Examples:

• po gradu = around the city
• po kući = around the house
• po stolu = over/on the table

Trčati is imperfective, and that fits the meaning well because it describes an ongoing or repeated activity.

The sentence is not about a single completed act of running. It is about the children being active again for some time:

• djeca će opet trčati = the children will be running again / will run around again

By contrast, otopliti se is perfective, because it refers to a change that happens as a complete event: it gets warmer.

So the aspect contrast is natural:

• ako se otopli → one change happens
• djeca će trčati → ongoing activity follows

The given word order is very natural, but Croatian word order is fairly flexible.

Standard neutral order:

• Ako se poslije kiše otopli, djeca će opet trčati po dvorištu.

You could change parts for emphasis, for example:

• Djeca će opet trčati po dvorištu ako se poslije kiše otopli.

That still means the same thing, but the focus feels a little different. Croatian often moves words around more freely than English, especially for emphasis, rhythm, or style.

Yes. It sounds completely natural.

It is a normal everyday sentence with:

• a common conditional structure (ako...)
• natural vocabulary (poslije kiše, djeca, trčati, dvorište)
• standard future tense (će trčati)

A native speaker might also say very similar variants, such as:

• Ako se nakon kiše otopli, djeca će opet trčati po dvorištu.
• Ako poslije kiše bude toplije, djeca će opet trčati po dvorištu.

But the original sentence is idiomatic and correct.