tokuni huyu ha hiatari ga warui heya da to, hiruma de mo samui desu.

特に means especially / particularly / in particular. It highlights that the statement is most true or most noticeable in winter.

Putting it near the beginning is natural because it sets the tone for the whole sentence:

• 特に冬は... = especially in winter...

Japanese adverbs are fairly flexible, but sentence-initial position is very common when the speaker wants to frame the whole statement.

冬は makes winter the topic or contrast point:

• 冬は = as for winter / in winter, especially
• 冬に = more simply in winter

Here, は works well because the speaker is singling out winter as the important case. It also matches the nuance of 特に.

So the feeling is not just in winter, but more like:

• winter, in particular
• when it comes to winter

日当たり refers to how much sunlight a place gets, especially a room, house, or spot.

So:

• 日当たりがいい = gets good sunlight
• 日当たりが悪い = gets poor sunlight / does not get much sun

It is a very common word when talking about rooms, apartments, and houses.

With 日当たり, Japanese naturally uses いい and 悪い.

So 日当たりが悪い does not mean sunlight itself is morally bad. It means the sun exposure is poor.

A natural English equivalent is:

• a room with poor sunlight
• a room that doesn't get much sun

This is just the normal Japanese collocation.

Because Japanese puts modifying information before the noun.

So:

• 日当たりが悪い部屋 = a room that gets poor sunlight

In English, we often need that or which:

• a room that gets little sunlight

Japanese does not need a relative pronoun here. The whole clause 日当たりが悪い directly modifies 部屋.

Yes. 日当たりの悪い部屋 is also very natural.

Both are used:

• 日当たりが悪い部屋
• 日当たりの悪い部屋

The difference is small here. Very roughly:

• 日当たりが悪い部屋 feels like a straightforward clause modifying 部屋
• 日当たりの悪い部屋 feels a bit more like a set descriptive phrase

In everyday Japanese, both are fine.

Here, だと is:

• だ = plain copula
• と = conditional

So:

• 日当たりが悪い部屋だと = if it is a room with poor sunlight / when it's a room with poor sunlight

Because 部屋 is a noun, Japanese uses だ before と in plain style.

The conditional と often sounds like a general tendency, natural result, or predictable consequence.

That fits this sentence well:

• if a room gets poor sunlight, it is cold even in the daytime, especially in winter

So と gives the feeling of:

• when that is the case, this naturally happens
• that kind of condition leads to that result

Compared with other conditionals:

• たら can sound more like a specific case or event
• なら can sound more like if that's the case or if you're talking about...

Here, と is a good match for a general fact.

This is very normal in Japanese.

In polite speech, the main sentence ending is often polite, but subordinate parts such as conditionals usually stay in plain form.

So this pattern is natural:

• 部屋だと、寒いです

Not:

• 部屋ですと、寒いです in ordinary conversation

So the rule of thumb is:

• inside the sentence: often plain
• sentence ending: polite if the speaker wants polite style

Here, でも means even, not but.

So:

• 昼間でも寒いです = it is cold even in the daytime

That is an important beginner point: でも has more than one use. In this sentence, it is the even meaning.

So the nuance is:

• not only at night
• even during the day, it is cold

Because 寒い is an い-adjective.

With い-adjectives, the polite form is:

• 寒いです

You do not add だ after an い-adjective.

Compare:

• 部屋だ = noun + だ
• 寒いです = い-adjective + です

So:

• 寒いだ is incorrect
• 寒いです is correct

Japanese often leaves the subject unstated when it is clear from context.

Here, the implied subject is something like:

• such a room
• that kind of room
• the room/apartment being discussed

So the sentence does not need to say it or the room explicitly. English usually does, but Japanese often does not.