hanadumari ga hidoi hi ha, nodo mo kawakiyasui node mizu wo yoku nomu.

鼻づまり is a noun meaning nasal congestion / a stuffy nose.

• 鼻づまり = the condition itself
• 鼻が詰まる = the nose gets blocked / clogged

So:

• 鼻づまりがひどい = the nasal congestion is bad
• 鼻が詰まっている = the nose is clogged

They are closely related, but 鼻づまり is the more compact noun form used a lot in everyday Japanese.

In 鼻づまりがひどい, the が marks 鼻づまり as the thing being described by ひどい.

So the structure is:

• 鼻づまりがひどい = the nasal congestion is severe

This is very natural in Japanese. Even though English might say I have bad nasal congestion, Japanese often describes the condition directly instead of centering the person.

Yes, but more specifically, the whole phrase 鼻づまりがひどい modifies 日.

So:

• 鼻づまりがひどい日 = a day when my nasal congestion is bad

This is a very common Japanese pattern: a full clause can come before a noun and describe it.

Examples of the same pattern:

• 雨が降る日 = a day when it rains
• 忙しい日 = a busy day
• 頭が痛い日 = a day when I have a headache

So here, ひどい is not directly saying the day itself is terrible. It is part of the clause describing what kind of day it is.

The は marks 鼻づまりがひどい日 as the topic:

• 鼻づまりがひどい日は、… = As for days when my congestion is bad, ...

This sets the condition or context for the rest of the sentence.

So the sentence structure is basically:

• On days when my nasal congestion is bad, ...

This kind of X は、Y structure is very common when talking about habits, general tendencies, or what happens under certain circumstances.

In this sentence, 日 is read ひ because it means day in the everyday sense:

• 鼻づまりがひどい日 = days when nasal congestion is bad

This reading is common in expressions like:

• 暑い日 = hot day
• 雨の日 = rainy day
• 休みの日 = day off

It is not にち here.

も means also / too.

So:

• のども乾きやすい = my throat also tends to get dry

The sentence implies that nasal congestion is one problem, and the throat too is affected.

Without も, it would simply say:

• のどが乾きやすい = the throat tends to get dry

With も, it adds the idea of in addition.

乾きやすい comes from:

• 乾く = to dry
• 〜やすい = easy to do / tends to do

So 乾きやすい literally means easily dries, but in natural English here it means:

• tends to get dry
• gets dry easily

With body conditions, 〜やすい often describes a tendency rather than literal ease.

Examples:

• 疲れやすい = gets tired easily
• 風邪をひきやすい = catches colds easily
• 忘れやすい = tends to forget easily

So のども乾きやすい means the throat becomes dry more easily than usual.

Both ので and から can mean because, but they have different nuances.

• ので sounds a bit more explanatory, neutral, and soft
• から can sound more direct or assertive

Here:

• のども乾きやすいので = because my throat also tends to get dry

This fits the sentence well because the speaker is calmly explaining a reason for a habit.

Compare:

• 乾きやすいので、水をよく飲む = more explanatory
• 乾きやすいから、水をよく飲む = also correct, slightly more direct

Japanese often leaves out the subject when it is obvious from context.

Here, the natural interpretation is something like:

• When my nasal congestion is bad, my throat also gets dry easily, so I drink water often.

Japanese does not need to say 私は unless the speaker wants contrast, emphasis, or clarity.

This omission is extremely common in everyday Japanese.

It most naturally means drink water often.

よく usually means:

• often
• frequently
• sometimes well, depending on context

So:

• 水をよく飲む = I drink water frequently

In context, English might also allow I drink a lot of water, but the Japanese word よく focuses more on frequency than quantity.

If you wanted to emphasize quantity more clearly, Japanese might use something like:

• 水をたくさん飲む = drink a lot of water

The plain form is being used because the whole sentence is written in plain style.

You can think of it as the dictionary-style casual/plain form:

• 飲む = plain
• 飲みます = polite

The sentence is explaining a general habit:

• 水をよく飲む = I often drink water

If you wanted to make the whole sentence polite, you could say:

• 鼻づまりがひどい日は、のども乾きやすいので、水をよく飲みます。

Both are grammatically correct; the difference is just style and politeness.

It is talking about a general tendency or habit, not one specific day.

Two clues help show that:

• 鼻づまりがひどい日は = on days when my congestion is bad
• 水をよく飲む = plain present, often used for habitual actions

So the meaning is closer to:

• Whenever my nasal congestion is bad, my throat also tends to get dry, so I drink water often.

If it were about one specific past day, the sentence would likely look different, such as using past forms.

Yes, and the meaning would be very similar:

• 鼻づまりがひどいときは、のども乾きやすいので水をよく飲む。

This would mean something like:

• When my nasal congestion is bad, my throat also tends to get dry, so I drink water often.

The difference is subtle:

• 日 emphasizes days / occasions
• とき emphasizes the time / situation when it happens

In this sentence, 日 sounds very natural because the speaker is talking about certain kinds of days.