atsui hi wa, juusu yori mizu no hou ga ii to omoimasu.

On hot days, I think water is better than juice.

Breakdown of atsui hi wa, juusu yori mizu no hou ga ii to omoimasu.

• は: topic particle
• 水みず: water
• 暑あつい: hot
• が: subject particle

Questions & Answers about atsui hi wa, juusu yori mizu no hou ga ii to omoimasu.

Why is 暑い directly before 日? Is it working like hot day in English?

Yes. 暑い is an い-adjective, and in Japanese an い-adjective can directly modify a noun.

• 暑い日 = a hot day / hot days

You do not need な or any other word between them.

Compare:

• 暑い日 = a hot day
• 静かな日 = a quiet day

The second one uses な because 静か is a な-adjective, but 暑い is not.

Why is there a は after 日?

は marks 暑い日 as the topic of the sentence.

So 暑い日は means something like:

• As for hot days, ...
• On hot days, ...

It sets the situation or context for what follows. In natural English, we often do not translate it word-for-word, but it helps frame the statement.

Why doesn’t it say 暑いの日?

Because that would be incorrect here.

When an い-adjective modifies a noun, it attaches directly:

• 暑い日
• 寒い朝
• 新しい本

The particle の is not used between an い-adjective and the noun it modifies.

What does より mean here?