achime chuwoseo ginpareul ipgo mokdorido haesseo.

에 marks a point in time, so 아침에 means in the morning or this morning.

In Korean, many time expressions can take 에 when you want to show when something happened:

• 아침에 = in the morning
• 저녁에 = in the evening
• 3시에 = at 3 o’clock

So in this sentence, 아침에 tells you the time background for the rest of the sentence.

춥다 means to be cold. It is a ㅂ-irregular adjective.

When you attach -어서 / -아서, the ㅂ changes in this pattern:

• 춥다
• stem: 춥-
• ㅂ changes and combines with -어서
• becomes 추워서

So:

• 춥다 → 추워요
• 춥다 → 추워서

This is a very common irregular pattern. Similar examples:

• 덥다 → 더워요, 더워서
• 어렵다 → 어려워요, 어려워서

Here, -아서/-어서 means because or so.

So 추워서 means:

• because it was cold
• since it was cold
• it was cold, so...

In this sentence, it connects the reason to the result:

• 아침에 추워서 = because it was cold in the morning
• 긴팔을 입고 목도리도 했어 = I wore long sleeves and also wore a scarf

So the full idea is: Because it was cold in the morning, I wore long sleeves and also wore a scarf.

Yes, in many situations you could say 추우니까, and the meaning would be similar: because it’s/was cold.

But there is a slight nuance:

• 추워서 sounds more like a natural cause/result connection
• 추우니까 can sound a bit more like giving a reason, explanation, or justification

Compare:

• 추워서 긴팔을 입었어. = It was cold, so I wore long sleeves.
• 추우니까 긴팔을 입었어. = Since it was cold, I wore long sleeves.

Both are fine, but 추워서 feels very natural for describing what happened because of the weather.

Literally, 긴 means long and 팔 means arm, but 긴팔 is a set expression that means long sleeves or long-sleeved clothing.

So 긴팔을 입다 does not mean to wear long arms. It means:

• to wear a long-sleeved shirt
• to wear long sleeves
• to put on something with long sleeves

Related expressions:

• 반팔 = short sleeves / short-sleeved clothing
• 긴팔 셔츠 = long-sleeved shirt
• 반팔 티셔츠 = short-sleeved T-shirt

In casual Korean, people often just say 긴팔 or 반팔 without naming the exact clothing item.

-고 connects verbs and means and.

So:

• 입고 = wear/put on and
• 목도리도 했어 = also wore a scarf

This structure links two actions by the same subject:

• 긴팔을 입고
• 목도리도 했어

So the sentence is saying: I wore long sleeves and also wore a scarf.

In Korean, -고 is very common for joining actions in sequence or listing actions.

Examples:

• 밥을 먹고 잤어. = I ate and slept.
• 문을 열고 들어갔어. = I opened the door and went in.

This is a very natural Korean expression.

With some wearable items, Korean often uses 하다 to mean to wear/put on them, especially accessories or things attached around the body.

So:

• 목도리를 하다 = to wear a scarf
• 안경을 하다 = to wear glasses
• 마스크를 하다 = to wear a mask
• 넥타이를 하다 = to wear a necktie

For a scarf specifically, you may also hear:

• 목도리를 두르다 = to wrap a scarf around oneself

But 목도리(를) 했어 is very common in everyday speech and sounds natural.

도 means also or too.

So:

• 목도리를 했어 = I wore a scarf.
• 목도리도 했어 = I also wore a scarf.

It adds the idea that the scarf was an additional item, on top of the long sleeves.

The implied structure is:

• I wore long sleeves,
• and I also wore a scarf.

Because the two clothing items use different common verbs in Korean:

• 긴팔을 입다 = to wear long-sleeved clothing
• 목도리를 하다 = to wear a scarf

So Korean does not repeat 입다 for the scarf here, because 하다 is the natural verb for that item.

This is similar to how different kinds of clothing can use different verbs in Korean:

• 옷을 입다 = wear clothes
• 모자를 쓰다 = wear a hat
• 신발을 신다 = wear shoes
• 안경을 쓰다 / 하다 = wear glasses
• 목도리를 하다 / 두르다 = wear a scarf

English often uses wear for everything, but Korean splits this up by item.

The subject is omitted because Korean often leaves it out when it is obvious from context.

In this sentence, the understood subject is probably I:

• (나는) 아침에 추워서 긴팔을 입고 목도리도 했어.

But Korean does not need to say 나는 if the listener already understands who is being talked about.

This is extremely common in everyday Korean. Subjects and objects are often dropped when they are clear from context.

It mainly connects the actions as part of one situation: wore long sleeves and wore a scarf.

With -고, the actions can sometimes feel sequential, but in this sentence the main point is simply that both things were done because it was cold.

So the natural reading is:

• I wore long sleeves and also wore a scarf

not necessarily a strong emphasis on exact order.

했어 is the casual/informal polite level? Actually, more precisely, it is informal non-polite speech, often used:

• with close friends
• with younger people
• in diaries
• in casual conversation

Compare:

• 했어 = casual
• 했어요 = polite
• 했습니다 = formal

So the same sentence in a polite style would be:

• 아침에 추워서 긴팔을 입고 목도리도 했어요.

The grammar and meaning stay the same; only the speech level changes.

Yes, that is the natural interpretation.

The sentence structure is:

• 아침에 추워서 = it was cold in the morning / because it was cold in the morning
• 긴팔을 입고 목도리도 했어 = I wore long sleeves and also wore a scarf

So the cold weather is presented as the reason for the clothing choices.

It does not necessarily mean the speaker first felt cold for a long time and only later dressed differently. It simply gives the reason: because it was cold, I dressed warmly.