Gece pencere açık kalırsa üşüyebilirsin.

In Turkish, time words often work like adverbs without any extra preposition or case ending.

So gece here means at night / during the night.

This is very natural in Turkish:

• gece = at night
• sabah = in the morning
• yarın = tomorrow

English usually needs a preposition like at or in, but Turkish often does not.

Turkish does not have articles like English a and the.

So pencere can mean:

• a window
• the window

Which one is meant depends on context. In this sentence, English would usually say the window, but Turkish simply says pencere.

Because açık kalmak is a very common Turkish expression meaning to remain open / to stay open.

Breakdown:

• açık = open
• kalmak = to stay, remain
• açık kalmak = to stay open

So pencere açık kalırsa literally means if the window stays open or if the window remains open.

This often sounds more natural in Turkish than simply using olmak (to be), because the idea is that the window is left in that state for some time.

kalırsa can be broken down like this:

• kal- = stay, remain
• -ır = aorist/general-fact marker
• -sa = if conditional ending

So:

• kalırsa = if it stays / if it remains

In sentences like this, the aorist + conditional is very common for real, general, or likely conditions.

Turkish often leaves subjects out when the verb already makes them clear.

In this sentence:

• pencere is the subject of kalırsa
• -sin in üşüyebilirsin shows the subject is you singular

So Turkish does not need to say sen unless it wants emphasis.

If you added it:

• Gece pencere açık kalırsa sen üşüyebilirsin.

That would sound more emphatic, like you might get cold.

It breaks down like this:

• üşü- = feel cold, get cold
• -yebil- = can / may / be able to
• -irsin = 2nd person singular ending in this form

So üşüyebilirsin literally means:

• you can get cold
• you may get cold
• you might feel cold

In this sentence, it is best understood as a warning or possibility: you might get cold.

Also note the y is just a buffer consonant to connect vowels smoothly.

Using -ebil- softens the statement and makes it about possibility.

Compare:

• üşürsün = you get cold / you will get cold
• üşüyebilirsin = you might get cold / you could get cold

In warnings, Turkish often prefers this softer possibility form, especially when the result is possible rather than absolutely certain.

So this sentence sounds natural and less blunt.

Because pencere is not the object here; it is the thing that stays open.

In:

• pencere açık kalırsa

the window is the subject of kalmak.

You would use pencereyi if the window were a direct object, for example:

• Pencereyi açtım. = I opened the window.

So:

• pencere açık kalırsa = if the window stays open
• pencereyi açık bırakırsan = if you leave the window open

Those are related, but grammatically different.

Yes, that is also a very natural sentence, but the focus changes.

• Gece pencere açık kalırsa üşüyebilirsin.

  • If the window stays open at night, you might get cold.
  • Focus: the state of the window

• Gece pencereyi açık bırakırsan üşüyebilirsin.

  • If you leave the window open at night, you might get cold.
  • Focus: your action

So the original sentence is a bit less direct about who caused the window to be open.

Turkish very often puts the if clause before the main clause:

• Gece pencere açık kalırsa üşüyebilirsin.

This is the most neutral and common order.

You can sometimes reverse the order for style or emphasis, but the clause-first order is very typical in Turkish.

So for learners, it is a good default pattern:

• [condition] + [result]

üşümek means to feel cold or to get cold physically.

It does not mean to catch a cold as an illness.

So:

• Üşüdüm. = I got cold / I felt cold.

For the illness a cold, Turkish uses different expressions, such as:

• soğuk algınlığına yakalanmak = to catch a cold

That is an important distinction.

It can absolutely mean at night here.

This is common in Turkish: a time noun is often used directly as a time adverb.

So:

• Gece çalışıyorum. = I work at night.
• Gece pencere açık kalırsa... = If the window stays open at night...

The exact English translation depends on context, but the Turkish form is perfectly normal.

It can work for either a general warning or a specific likely situation, depending on context.

Because of the forms:

• kalırsa = if it stays
• üşüyebilirsin = you might get cold

the sentence sounds like a practical warning:

• If the window stays open at night, you might get cold.

So it is not a hard scientific rule, but a likely consequence.

That is why the grammar feels softer and more natural than a more absolute statement.