sumaho ni ooame no keihou ga todoita node, kyou ha hayame ni ie ni kaerimasita.

Here, に marks the destination or recipient of something.

So スマホに届いた means arrived on / was delivered to the smartphone.

A very literal breakdown would be:

• スマホに = to the smartphone
• 警報が届いた = an alert arrived

In natural English, we would usually say An alert came to my phone or My phone received a heavy rain warning.

Japanese often uses に with verbs like 届く when something reaches a person, place, or device.

の connects two nouns.

• 大雨 = heavy rain
• 警報 = warning / alarm / alert

So 大雨の警報 means a heavy rain warning or a warning for heavy rain.

This use of の is very common in Japanese. It often works like:

• possession: 私の本 = my book
• category/type: 日本の車 = Japanese car
• content/topic: 天気のニュース = weather news

Here, 大雨の警報 is basically a warning concerning heavy rain.

が marks 警報 as the subject of 届いた.

So the sentence structure is:

• 警報が届いた = the warning arrived

This is natural because the alert is the thing that performed the action of arriving.

If you think of it literally:

• スマホに = to the smartphone
• 警報が = the warning
• 届いた = arrived

So が is used because the warning is what arrived.

Both can sometimes be translated as came, but 届く has a stronger sense of reaching its destination.

For example:

• 荷物が届く = a package is delivered / arrives
• メールが届く = an email arrives
• 通知が届く = a notification arrives

So 警報が届いた sounds very natural for an alert that was sent to a phone.

Using 来た would focus more on the idea that it came, while 届いた emphasizes that it was received / reached the phone.

Both ので and から can mean because, but they feel a little different.

• ので sounds softer, more explanatory, and a bit more formal
• から sounds more direct and conversational

In this sentence:

• 警報が届いたので、今日は早めに家に帰りました。
• Because a heavy rain warning came to my phone, I went home early today.

Using ので fits well because the speaker is calmly explaining the reason for going home early.

Compare:

• 雨だから帰る。 = I’m going home because it’s raining.
  
  • more direct
• 雨なので帰ります。 = I’m going home because it’s raining.
  
  • more explanatory/polite

今日 means today, and は marks it as the topic.

So 今日は means something like:

• as for today
• today, ...

This helps frame the rest of the sentence:

• 今日は早めに家に帰りました
• As for today, I went home a bit early

The は can also give a slight sense of contrast, like today at least or today in particular, depending on context. Even if that contrast is weak, 今日は is a very natural way to set the scene.

Not exactly.

• 早く = early / quickly, depending on context
• 早めに = a little early / earlier than usual / on the early side

So 早めに家に帰りました means:

• I went home a bit early
• I went home earlier than usual

The ending 〜め often adds the nuance of somewhat or on the ... side.

Examples:

• 小さめ = somewhat small / on the small side
• 多め = somewhat much / a bit extra
• 早め = somewhat early

The に turns 早め into an adverb, so it can modify the verb 帰りました.

They are doing different jobs.

• 早めに: the に makes 早め function adverbially
  
  • early / a bit early
• 家に: the に marks the destination
  
  • to home

So:

• 早めに = early-ish / a bit early
• 家に帰りました = went home

It just happens that both use に, but the grammar is different in each case.

Both are possible.

• 家に帰る
• 家へ帰る

Both can mean go home.

The difference is subtle:

• に often emphasizes the destination more directly
• へ emphasizes direction or movement toward something

With 帰る, に is extremely common and very natural. So 家に帰りました is a standard way to say went home.

In this sentence, 家 is best understood as home.

Even though 家 can literally mean house, with 帰る it very often means go home.

So:

• 家に帰る = go home

This is one of those cases where the natural English translation is not the most literal one.

Japanese often leaves out information that is obvious from context.

In English, we often say:

• my phone
• my house
• I went home

In Japanese, if it is clear whose phone or home is being talked about, it is usually omitted.

So:

• スマホに警報が届いた naturally means an alert came to my smartphone
• 家に帰りました naturally means I went home

Adding 私の would usually be unnecessary unless the speaker wanted emphasis or contrast.

Because both actions are being described as completed events.

• 届いた = arrived
• 帰りました = went home

The speaker is talking about what happened:

1. the warning arrived on the phone
2. because of that, they went home early

So the past tense is natural.

Also, 帰りました is in polite form:

• dictionary form: 帰る
• polite present/future: 帰ります
• polite past: 帰りました

Japanese word order is more flexible than English, but some parts naturally stay together.

For example, these pieces are important units:

• スマホに
• 大雨の警報が
• 届いたので
• 今日は
• 早めに
• 家に
• 帰りました

The original sentence is very natural: スマホに大雨の警報が届いたので、今日は早めに家に帰りました。

Some reordering is possible for emphasis, but not every order sounds equally natural. For learners, it is best to treat this sentence pattern as:

Reason + ので, result

So:

• [警報が届いたので]、[早めに帰りました]
• Because an alert arrived, I went home early

No. They are related, but not the same.

• 注意報 = advisory / warning to be careful
• 警報 = stronger warning / alarm

So 警報 usually suggests a more serious situation than 注意報.

In weather reports, this distinction is important. A learner might not need every technical detail right away, but it is useful to know that 警報 sounds more urgent.

A helpful breakdown is:

• スマホに = to my smartphone
• 大雨の警報が = a heavy rain warning
• 届いたので = because it arrived
• 今日は = today / as for today
• 早めに = a bit early
• 家に = home
• 帰りました = went

So the structure is:

[Reason] ので、[result].

This is a very common Japanese pattern:

• 電車が遅れたので、遅刻しました。
  • Because the train was delayed, I was late.
• 雨が降っているので、傘を持って行きます。
  • Because it’s raining, I’ll take an umbrella.

Your sentence follows the same pattern exactly.