kyou ha harete atui node, hiyakedome wo nutte kara dekakeru.

今日 は sets today up as the topic of the sentence.

So the sentence is talking about as for today...

This does not necessarily mean today is the grammatical subject. It is just the thing the speaker is framing the statement around. In English, we often do this without noticing, with expressions like:

• As for today, ...
• Today, ...

Japanese uses は very often for that kind of topic marking.

晴れて comes from 晴れる, a verb meaning to clear up / to be sunny.

Here, the て-form connects it to the next part:

• 晴れて暑い = it is sunny and hot

A common learner question is: why not use an adjective-like form? The reason is that 晴れる is a verb, not an い-adjective. So it connects as a verb:

• 晴れる → 晴れて

This is similar to saying:

• The weather is sunny and hot

in one smooth phrase.

Because 晴れ is not an い-adjective like 暑い.

Compare:

• 暑い = an い-adjective
• 晴れる = a verb

So they behave differently:

• 暑い → 暑くて when linking adjectives
• 晴れる → 晴れて when linking verbs

That is why 晴れて暑い is correct:
sunny and hot

Because ので attaches to the plain form of what comes before it.

So:

• 暑いので = because it is hot
• 晴れて暑いので = because it is sunny and hot

This is normal Japanese grammar. You do not need to change 暑い into another connective form here, because ので is already doing the job of linking the reason to the result.

Both can mean because, but they have slightly different nuance.

• から is more direct and conversational
• ので often sounds a little softer, more explanatory, or more neutral

So:

• 晴れて暑いから、日焼け止めをぬってから出かける。
• 晴れて暑いので、日焼け止めをぬってから出かける。

Both are natural, but ので can sound a bit more like calmly giving a reason.

日焼け止め literally breaks down like this:

• 日焼け = sunburn / tanning from the sun
• 止め = stopper / prevention

So 日焼け止め means something that prevents sunburn, which in natural English is sunscreen or sunblock.

Because 日焼け止め is the direct object of ぬる.

• 日焼け止めをぬる = to apply sunscreen

The particle を marks the thing being acted on.

So here, the speaker is doing the action ぬる to 日焼け止め.

Because this sentence uses the て-form of ぬる to connect it with から.

• ぬる = to apply / spread
• ぬって = te-form
• ぬってから = after applying

The ます-stem ぬり is used in other patterns, but not here.

For example:

• ぬってから出かける = correct
• ぬりから出かける = incorrect

〜てから means after doing ...

So:

• 日焼け止めをぬってから出かける
• I go out after applying sunscreen

This pattern shows sequence:

1. apply sunscreen
2. go out

It is very common in Japanese for one action to happen first, and then another action follows.

The two から have different jobs.

1. In 晴れて暑いので, there is no から there in this sentence, but learners often compare it with から meaning because
2. In ぬってから, から means after

So if the sentence had used 暑いから, that から would mean because. But the actual から in this sentence is part of 〜てから, meaning after doing

This is a good reminder that から can have more than one function in Japanese depending on the pattern.

Because Japanese often omits subjects when they are obvious from context.

In this sentence, the person who applies sunscreen and goes out is very likely the speaker, so Japanese does not need to say 私は.

A full version could be:

• 私は、今日は晴れて暑いので、日焼け止めをぬってから出かける。

But that sounds less natural unless there is a reason to emphasize I.

Japanese frequently leaves out information that English normally includes.

This sentence is written in the plain style.

• 出かける = plain form
• 出かけます = polite form

So the whole sentence matches that style:

• 晴れて
• 暑い
• ぬって
• 出かける

If you wanted a polite version, you could say:

• 今日は晴れて暑いので、日焼け止めをぬってから出かけます。

Both are correct; the difference is formality.

Not exactly. 出かける means to go out, to head out, or to leave the house for somewhere.

So it is more specific than just 行く.

Compare:

• 行く = go
• 出かける = go out / head out

In this sentence, 出かける fits well because the idea is that the speaker is going out after putting on sunscreen.

Yes. A sentence like this is also possible:

• 今日は晴れていて暑いので、日焼け止めをぬってから出かける。

晴れていて can sound a little more explicitly like it is sunny and...

But 晴れて暑い is also natural and concise. In everyday Japanese, both kinds of linking can appear.

No, the comma is not strictly necessary, but it is very common and helpful.

It separates the reason part from the main action:

• 今日は晴れて暑いので、 = reason
• 日焼け止めをぬってから出かける。 = main action

Japanese punctuation is often more flexible than English punctuation, so you may see the sentence with or without the comma.