Ağustos çok sıcak geçerse, dışarı çıkarken su taşımalıymışız.

In this sentence, sıcak geçmek is an idiomatic way to talk about how a period of time goes.

• geçmek usually means to pass or to go by
• with words like yaz (summer), kış (winter), gün (day), hafta (week), Ağustos (August), it can mean to be spent / to go / to turn out
• so Ağustos çok sıcak geçerse means something like if August is very hot or if August goes very hot

It does not mean someone is physically passing somewhere hot. It is about the character of the month.

-se / -sa is the Turkish conditional ending, meaning if.

So:

• geçer = it passes / it goes
• geçerse = if it passes / if it goes

In this sentence:

• Ağustos çok sıcak geçerse = if August is very hot / if August turns out very hot

The form geçer here is the aorist-based stem often used before the conditional.

Not necessarily. Even though geçmek literally means to pass, in expressions about time periods it often describes how that period is going overall.

So Ağustos çok sıcak geçerse can be understood as:

• if August is very hot
• if August turns out very hot
• if August ends up being very hot

It is more about the nature of the month than about waiting until the month is completely over.

Because Ağustos is the subject of the conditional clause.

In Ağustos çok sıcak geçerse:

• Ağustos = the thing being described
• çok sıcak = very hot
• geçerse = if it goes / if it turns out

Turkish subjects often appear with no extra case ending. That is normal.

dışarı çıkarken means when going outside or while going outside.

Breakdown:

• dışarı = outside
• çıkmak = to go out
• çıkarken = when/while going out

The ending -ken adds the meaning while or when doing something.

So:

• dışarı çıkarken su taşımalıymışız = apparently we should carry water when going outside

Both are possible in Turkish, but they give slightly different nuances.

• çıkarken = while going out / when going out
• çıkınca = when one goes out / after going out

In this sentence, çıkarken fits well because it describes the situation or occasion in which carrying water is advisable.

It sounds like:

• when heading outside, we should have water with us

So -ken feels natural here.

Because su is being used in a general, non-specific sense.

In Turkish, a direct object is often left unmarked when it is indefinite or general:

• su taşımak = to carry water
• kitap okumak = to read books / read a book in a general sense

If you said suyu, that would usually suggest the water or some specific water already known in context.

Here the meaning is general:

• carry water
• not carry the water

This is the most packed part of the sentence.

It can be broken down like this:

• taşı- = carry
• -malı = should / must
• -ymış = apparently / it seems / reportedly
• -ız = we

So taşımalıymışız means something like:

• apparently we should carry
• it seems we should carry
• we are said to need to carry

It combines necessity with reported or inferred information.

That y is a buffer consonant.

Turkish often inserts y between two vowels so the word is easier to pronounce.

Here:

• taşımalı ends in a vowel
• -mış also begins with a vowel-like sound structure that needs linking

So Turkish uses:

• taşımalıymışız not
• taşımalımışız

This linking y is very common in Turkish grammar.

This is an important nuance.

• taşımalıyız = we should carry
  This is direct. The speaker states it plainly.

• taşımalıymışız = apparently we should carry / it seems we should carry
  This is indirect. It can mean the speaker learned this from someone else, read it somewhere, or is arriving at the conclusion indirectly.

So -mış adds a sense of:

• reported information
• hearsay
• discovery
• indirectness

It makes the statement less direct than taşımalıyız.

Yes, grammatically -ız means we.

But in Turkish, we can sometimes be used a bit broadly, especially in advice or general statements. It may mean:

• the speaker and listener together
• people like us
• people in general in this situation

So here it can sound like:

• we should carry water
• people should carry water
• one should carry water

depending on context.

Yes, both can work, but they are slightly different.

• taşımak = to carry, to have on you, to transport
• götürmek = to take something somewhere

So:

• su taşımak emphasizes carrying water with you
• su götürmek emphasizes taking water along to a place

In this sentence, taşımak fits the idea of having water on you when you go outside.

Because of -malıymışız, it sounds most like reported advice or a conclusion the speaker has heard or realized.

It can feel like:

• someone told us this
• we found out this is what we should do
• apparently this is the recommended thing

So it is not as direct and forceful as a plain rule like su taşımalıyız. It has a slightly more indirect, reported tone.