harete iru uti ni, sentakumono wo beranda ni hosite okimasu.

晴れる means to become clear / to clear up.
In this sentence, 晴れている describes the current state: it is clear / it is sunny.

So:

• 晴れる = the weather clears up
• 晴れている = the weather is currently clear

Because the sentence means doing something while it is still sunny, the ongoing state 晴れている is the natural choice.

うちに means something like while..., during the time that..., or before that situation changes.

In 晴れているうちに, it means:

• while it is still sunny
• before it stops being sunny

This expression often carries the nuance that the current condition will not last forever, so you should do something during that window of time.

Examples:

• 熱いうちに食べてください。
  Please eat it while it’s still hot.

• 若いうちに勉強したほうがいい。
  It’s better to study while you’re young.

So here, the speaker is saying they will hang the laundry out while the weather is still good.

In うちに, the particle に marks the time point or time frame in which the action happens.

So 晴れているうちに means:

• during the period when it is sunny
• while it is still sunny

This に is part of the common grammar pattern X うちに.

Compare:

• 日本にいるうちに、たくさん旅行したい。
  I want to travel a lot while I’m in Japan.

• 忘れないうちに、メモしてください。
  Please make a note before you forget.

So it is best to learn うちに as one set expression.

洗濯物 means laundry, especially clothes or other things that have been washed.

It refers to the items themselves, not the act of washing.

Compare:

• 洗濯 = washing laundry / doing the laundry
• 洗濯物 = the laundry items, the clothes being washed or dried

In this sentence, 洗濯物を干す means to hang out the laundry to dry.

This is a very common question.

With 干す, the particle に often marks the place where something is put or hung. The focus is on the destination/location of placement.

So:

• ベランダに干す = hang it on / in / out on the balcony

Here, the laundry is being placed onto the balcony area to dry.

You may sometimes see で with location-based actions, but 干す very naturally takes に when talking about where the item is hung.

A similar pattern is:

• 壁に貼る = stick it on the wall
• 枝にぶら下げる = hang it from a branch

So ベランダに干す is the expected expression.

干しておきます is 干す + ておく.

ておく often means:

1. do something in advance
2. do something and leave it that way
3. do something as a preparation

So:

• 干します = I will hang the laundry
• 干しておきます = I’ll hang the laundry out for now / in advance / so it will be ready / and leave it hanging

In this sentence, the nuance is something like:

• I’ll hang the laundry out while it’s still sunny
• I’d better get the laundry out on the balcony while the weather is still good

It sounds more purposeful and practical than plain 干します.

Very often, yes, but not only that.

ておく can mean:

• do something beforehand
  会議の前に、資料を読んでおきます。
  I’ll read the materials beforehand.

• do something and leave it in that state
  窓を開けておきます。
  I’ll leave the window open.

In 干しておきます, both ideas fit nicely:

• hang the laundry out before the weather changes
• hang it out and leave it there to dry

So this is a very natural use of ておく.

Japanese non-past forms cover both:

• present/future actions
• habitual actions

So 干しておきます can mean:

• I’ll hang it out
• I hang it out
• I’m going to hang it out

Depending on context.

Here, it most naturally sounds like an intended action:
I’ll hang the laundry out on the balcony while it’s still sunny.

Japanese does not always separate present and future as clearly as English does.

The subject is omitted because Japanese often leaves out information that is obvious from context.

In this sentence, the understood subject is probably:

• I
• or we, depending on context

So the full idea is something like:

• I’ll hang the laundry out on the balcony while it’s still sunny.

Japanese does this all the time when the subject is clear or not important.

A more explicit version could be:

• 私は、晴れているうちに、洗濯物をベランダに干しておきます。

But in normal conversation, 私は is often unnecessary.

In 晴れている, いる is the auxiliary verb in the ている pattern, not the main verb to exist.

Auxiliary verbs like this are very commonly written in hiragana:

• 食べている
• 読んでいる
• 晴れている

Writing it as 居る here would usually look unnatural or overly formal.
So いる in kana is standard.

Yes, absolutely. It is a very useful pattern.

It means while it’s still sunny or before the weather changes, so you can use it with many actions that depend on good weather.

For example:

• 晴れているうちに、買い物に行きましょう。
  Let’s go shopping while it’s still sunny.

• 晴れているうちに、散歩してきます。
  I’ll go for a walk while it’s still sunny.

• 晴れているうちに、写真を撮りたい。
  I want to take pictures while it’s still sunny.

So once you understand X うちに, you can use it very broadly.

It is very close, and balcony is usually the best translation.

However, Japanese ベランダ often refers to the outside space attached to an apartment or house, especially one used for drying clothes. In everyday Japanese life, ベランダに洗濯物を干す is a very common image.

So balcony is a good translation, but the Japanese word may feel especially connected to practical household use.

The sentence breaks down like this:

• 晴れているうちに
  while it is still sunny

• 洗濯物を
  the laundry

• ベランダに
  on the balcony

• 干しておきます
  will hang out / will hang out in advance

So the structure is:

[time condition] + [object] + [place] + [action]

More literally:

While it is still sunny, I’ll hang the laundry out on the balcony.

This is a very natural everyday Japanese sentence.