Soğuk havada kalınca çok hapşırıyorum.

It breaks down like this:

• soğuk = cold
• hava = air / weather
• -da = the locative ending, meaning in / at / on

So soğuk havada literally means in cold weather or in the cold air. In natural English, you would often just say in the cold.

Because Turkish uses the locative case here.

• hava = weather / air
• havada = in the weather / in the air

The sentence is describing the situation or environment where the sneezing happens, so Turkish marks that with -da / -de.

This is very common:

• evde = at home
• okulda = at school
• soğuk havada = in cold weather

kalınca comes from the verb kalmak, which usually means to stay, to remain, or sometimes to be left somewhere.

Here:

• kal- = verb stem
• -ınca = when / once / whenever

So kalınca means when (I) stay or more naturally here, when I’m in / when I’m exposed to.

In this sentence, soğuk havada kalınca is best understood as:

• when I stay in cold weather
• when I’m out in the cold
• when I’m exposed to cold weather

Its basic meaning is when or once. In many real sentences, though, it can feel a bit like if/whenever, especially when describing a repeated result.

So in this sentence:

• Soğuk havada kalınca çok hapşırıyorum.

it means something like:

• When I’m in cold weather, I sneeze a lot
• Whenever I’m out in the cold, I sneeze a lot

So it is mainly when, but in habitual situations it can sound like whenever.

In Turkish, the -ınca clause often does not show the subject explicitly if it is the same as the subject of the main verb.

Here the main verb is:

• hapşırıyorum = I sneeze / I am sneezing

Because that verb clearly shows I, Turkish naturally understands kalınca as when I stay / when I’m in.

So the subject of both parts is the same person:

• I stay in the cold
• I sneeze a lot

Turkish often leaves this kind of thing implicit.

Good question. Both forms are possible in Turkish, but they can feel slightly different.

• hapşırıyorum = literally I am sneezing, but it is also often used for a repeated personal tendency in everyday speech
• hapşırırım = I sneeze, more general/habitual, sometimes more neutral or matter-of-fact

So:

• Soğuk havada kalınca çok hapşırıyorum feels very natural in conversation: When I’m out in the cold, I sneeze a lot
• Soğuk havada kalınca çok hapşırırım is also understandable, but sounds a bit more like a general rule or habit

In modern spoken Turkish, -yor is often used where English would simply use the present simple.

Because the verb already tells you the subject.

• hapşırıyorum ends in -um, which shows I

So Turkish does not need ben unless you want emphasis.

• Hapşırıyorum = I sneeze / I’m sneezing
• Ben hapşırıyorum = I am the one sneezing or I sneeze with extra emphasis

Leaving out subject pronouns is very normal in Turkish.

Here çok means a lot.

• çok hapşırıyorum = I sneeze a lot

This is different from English, where very and a lot are separate. In Turkish, çok can cover both ideas depending on what it modifies:

• çok soğuk = very cold
• çok hapşırıyorum = I sneeze a lot

So in this sentence, çok modifies the verb hapşırıyorum.

Because in Turkish, adverbs like çok usually come before the word they modify.

So:

• çok hapşırıyorum = I sneeze a lot

This is normal Turkish word order. English often puts a lot after the verb, but Turkish usually places çok before it.

Not completely, but the given order is very natural.

• Soğuk havada kalınca çok hapşırıyorum.

This follows a common Turkish pattern:

1. condition / situation first
2. main result second

So it feels like:

• When I’m in the cold, I sneeze a lot

Turkish word order is flexible, but this version is smooth and standard. A comma is also often written:

• Soğuk havada kalınca, çok hapşırıyorum.

Both.

Grammatically, -ınca gives a time meaning: when.

But in real usage, it often also suggests a cause/result relationship. So the sentence means not only:

• when I’m in cold weather

but also implicitly:

• because being in cold weather triggers it

So the full idea is:

• When I’m out in the cold, I end up sneezing a lot

Yes. That is a very natural alternative.

• soğukta = in the cold
• soğuk havada = in cold weather

So:

• Soğukta kalınca çok hapşırıyorum
• Soğuk havada kalınca çok hapşırıyorum

Both work. The first is a bit shorter and more direct; the second is a little more explicit.

The main ones are:

• ğ in soğuk: this letter usually is not pronounced like a hard g. It often lengthens or smooths the surrounding vowels.
  So soğuk sounds roughly like so-uk.
• ş in hapşırıyorum: pronounced like sh
• ı in hapşırıyorum: this is the Turkish dotless i. It is not exactly an English sound, but it is somewhat like a relaxed uh sound made without rounding your lips.

A rough learner-friendly pronunciation might be:

• Soğuk havada kalınca çok hapşırıyorum
• so-uk ha-va-da ka-lın-ja chok hap-shuh-rı-yo-rum

That is only approximate, but it helps with the main sounds.