Pada September, udara pagi di taman terasa sejuk.

Here, pada means something like in or during when talking about time.

So:

• pada September = in September

In Indonesian, pada is often used before points or periods of time, especially in more neutral or formal-style sentences.

Examples:

• pada hari Senin = on Monday
• pada pagi hari = in the morning
• pada September = in September

In everyday speech, Indonesians may sometimes also say just September without pada, depending on context, but pada September is very natural and clear.

The comma separates the time phrase from the main clause:

• Pada September, = In September,
• udara pagi di taman terasa sejuk. = the morning air in the park feels cool.

This is similar to English, where a time expression at the beginning is often followed by a comma:

• In September, the morning air in the park feels cool.

The comma is helpful but not always absolutely required in informal writing. It is standard and natural here.

Udara means air, and pagi means morning.

Together, udara pagi means:

• morning air

This is a noun phrase where pagi describes udara. Indonesian often puts the main noun first and the describing word after it.

Compare:

• udara pagi = morning air
• angin malam = night wind
• sinar matahari = sunlight

So it is not literally a full sentence part like air that is morning, but simply the normal Indonesian way to say morning air.

Because Indonesian usually puts the head noun first and the modifier after it.

So:

• udara pagi = air + morning = morning air

This is different from English, which often puts the describing word before the noun:

• morning air

More examples:

• rumah besar = big house
• kopi panas = hot coffee
• hujan deras = heavy rain

So pagi udara would sound unnatural in standard Indonesian.

Di taman means in the park.

• di = in / at
• taman = park

In this sentence, di taman most naturally describes where the morning air is being experienced:

• udara pagi di taman = the morning air in the park

So the structure is basically:

• Pada September = In September
• udara pagi di taman = the morning air in the park
• terasa sejuk = feels cool

Terasa means feels, is felt, or seems depending on context.

In this sentence:

• udara pagi di taman terasa sejuk
• the morning air in the park feels cool

It comes from rasa (feeling, taste, sense) and often expresses how something is perceived.

Some useful comparisons:

• Udara itu terasa dingin. = The air feels cold.
• Ruangan ini terasa nyaman. = This room feels comfortable.
• Hari ini terasa panjang. = Today feels long.

So terasa is a very natural word when talking about sensations or impressions.

Because terasa adds the meaning of feels/seems, not just simple description.

Compare:

• Udara pagi di taman sejuk.
  = The morning air in the park is cool.

• Udara pagi di taman terasa sejuk.
  = The morning air in the park feels cool.

The second version emphasizes sensory experience. It sounds a little more vivid and natural when describing weather or atmosphere.

Also, Indonesian often does not need a word like is/are in ordinary sentences:

• Udara itu sejuk. = The air is cool.

And adalah is usually not used before adjectives like this. It is mostly used in more formal definitions or equivalences:

• Jakarta adalah ibu kota Indonesia. = Jakarta is the capital of Indonesia.

So adalah sejuk would be wrong here.

Both can relate to cool/cold, but they are not exactly the same.

• sejuk = cool, pleasantly cool, refreshing
• dingin = cold

In this sentence, sejuk is chosen because it gives a comfortable, pleasant feeling.

Compare:

• Udara pagi terasa sejuk. = The morning air feels cool / pleasantly cool.
• Air itu dingin. = That water is cold.
• Cuacanya dingin sekali. = The weather is very cold.

So sejuk often has a more positive nuance than dingin.

Indonesian does not have articles that work like English a/an and the.

So:

• udara pagi di taman can mean the morning air in the park or just morning air in the park, depending on context.

Indonesian relies on context much more than English does for definiteness.

If needed, speakers can make things more specific in other ways, for example:

• udara pagi itu = that/the morning air
• sebuah taman = a park
• taman itu = the park / that park

But in many normal sentences, no article is needed.

Yes, to some extent, but changing the order can shift emphasis.

The original sentence:

• Pada September, udara pagi di taman terasa sejuk.

This is very natural because it starts with the time frame.

Other possible orders:

• Udara pagi di taman terasa sejuk pada September.
  This is also grammatical, but it places the time information later.

• Di taman, udara pagi terasa sejuk pada September.
  This emphasizes the location more.

Indonesian word order is often flexible, especially for time and place phrases, but the original sentence sounds smooth and neutral.

Yes.

• pada September = in September
• pada bulan September = in the month of September

Adding bulan makes it more explicit, but it is often unnecessary because September already clearly names a month.

So both are correct:

• Pada September, udara pagi di taman terasa sejuk.
• Pada bulan September, udara pagi di taman terasa sejuk.

The version without bulan is a little more concise.

Usually, pada September is better.

Although learners often think of di as in, di is mainly used for location:

• di taman = in the park
• di rumah = at home

For time expressions, Indonesian more often uses:

• pada for points/periods of time
• sometimes no preposition at all, depending on the expression

So:

• pada September = natural
• di September = generally not standard in careful Indonesian

A learner should usually choose pada here.

It is best understood here as an intransitive stative-type verb meaning to feel / to be محسوس as in the sense of perception.

Even though it has the prefix ter-, this is not the usual passive meaning that beginners may expect.

In this sentence:

• udara ... terasa sejuk
• the air feels cool

It is not saying someone actively feels the air. Instead, it describes how the air is perceived.

That is why terasa is common in descriptive sentences about atmosphere, mood, temperature, texture, and so on.

Examples:

• Masakannya terasa asin. = The food tastes salty.
• Suasananya terasa tenang. = The atmosphere feels calm.
• Beban itu terasa berat. = That burden feels heavy.

So the most useful way for a learner to understand it here is simply: terasa = feels / seems.