yeoreumeneun biga jaju waseo bangi neomu seuphal ttaega isseoyo.

에 marks a time expression, so 여름에 means in summer.

Adding 는 makes it 여름에는, which gives it a topic/contrast feeling. It is like saying:

• As for summer...
• In summer, at least...
• When it comes to summer...

So 여름에는 sounds a little more natural when the speaker is talking generally about what summer is like, or contrasting summer with other seasons.

가 is the subject marker, so 비가 자주 와서 simply means because rain comes/falls often.

Using 비는 would add contrast, as if you were saying something like:

• Rain, at least, falls often...
• As for rain, it comes often...

In this sentence, the speaker is just stating a fact, so 비가 is the most natural choice.

자주 means often or frequently.

It modifies the verb 오다 in 비가 자주 와서, so the idea is:

• the rain comes often
• more naturally in English: it rains often

Korean often uses 비가 오다 for to rain.

Yes, 오다 literally means to come, but in Korean 비가 오다 is the normal expression for it rains or rain falls.

So:

• 비가 와요 = It rains / It’s raining
• 비가 자주 와요 = It rains often

This is just a standard Korean expression, not something you usually translate word-for-word.

This is because 오다 combines with -아서/어서 irregularly in a very common way:

• 오다 + -아서 → 와서

So 와서 means because it comes or and so it comes, depending on context.

In this sentence, 와서 gives a cause/result meaning:

• because it rains often, the room is sometimes very humid

Here -아서/어서 connects two clauses and shows a reason or cause.

So:

• 비가 자주 와서 = because it rains often = it rains often, so...

In this sentence, the second part is the result:

• frequent rain → the room is sometimes very humid

This is one of the most common ways to say because in everyday Korean.

Here 방이 marks the room as the subject of 습하다.

So the structure is:

• 방이 습하다 = the room is humid

If you used 방은, it would sound more contrastive, like:

• As for the room, it gets humid...

That is possible in some contexts, but 방이 is the neutral choice here.

방에 would mean in the room, which is a different role. For example:

• 방에 습기가 많아요 = There is a lot of humidity in the room

But that is not the structure used in your sentence.

This is because 때 means time or when, and before 때 Korean uses the future/attributive form of adjectives and verbs:

• 습하다 → 습할 때 = when it is humid
• 가다 → 갈 때 = when [someone] goes
• 먹다 → 먹을 때 = when [someone] eats

So 습할 때 is the normal grammar pattern for when it is humid.

습한 is also an adjective form, but it is used directly before nouns:

• 습한 방 = a humid room
• 습한 날씨 = humid weather

So:

• 습한 방 = a humid room
• 습할 때 = when it is humid

Literally, 때가 있어요 means there are times.

So:

• 방이 너무 습할 때가 있어요 = There are times when the room is very humid = more naturally, Sometimes the room gets very humid

This pattern is very common:

• 바쁠 때가 있어요 = There are times when I’m busy
• 한국 음식이 그리울 때가 있어요 = There are times when I miss Korean food

It is a nice way to say sometimes with a bit more nuance than just using 가끔.

Yes, 너무 often means too in the sense of excessively, like too much.

So 너무 습하다 usually means:

• too humid
• very humid with a negative feeling

In modern spoken Korean, 너무 is also often used casually to mean just very, even in positive sentences. But here, because humidity is usually unpleasant, it keeps the too/excessively feeling quite naturally.

It can describe both.

습하다 means humid, damp, or moist in the air. So it works for:

• 날씨가 습해요 = The weather is humid
• 방이 습해요 = The room is humid
• 지하실이 습해요 = The basement is damp/humid

So using it for 방 is completely natural.

A helpful breakdown is:

• 여름에는 = in summer / as for summer
• 비가 자주 와서 = because it rains often
• 방이 = the room
• 너무 습할 때가 있어요 = there are times when it is very humid

So the whole structure is:

In summer, because it rains often, there are times when the room gets very humid.

This sentence has:

1. a time/topic phrase,
2. a cause clause,
3. a main clause describing what sometimes happens.

Yes. The original ends in polite style -어요.

A casual version would be:

• 여름에는 비가 자주 와서 방이 너무 습할 때가 있어.

The grammar is the same. Only the politeness level changes:

• 있어요 = polite
• 있어 = casual/plain spoken style

So the sentence in your example is appropriate for normal polite conversation.