Сегодня сильно дует ветер, поэтому я возьму тёплый шарф.

Russian word order is much more flexible than English word order. Putting сегодня first sets the time frame right away: Today, ...

So:

• Сегодня сильно дует ветер = Today the wind is blowing strongly / It’s very windy today
• Ветер сегодня сильно дует is also possible, but it puts more focus on ветер

In this sentence, starting with сегодня sounds natural because it introduces the situation first.

Because сильно is an adverb, and it describes the verb дует (blows).

• сильно дует = blows strongly
• сильный ветер = a strong wind

So compare:

• Сегодня сильно дует ветер = Today the wind is blowing strongly
• Сегодня сильный ветер = Today there is a strong wind

Both are natural, but they are built differently:

• сильно modifies the action
• сильный modifies the noun ветер

Yes, exactly. Russian often describes weather in a more literal way than English.

• дует ветер = the wind is blowing
• natural English often uses it’s windy

So Russian uses a normal subject + verb structure here:

• ветер = wind
• дует = blows / is blowing

This is completely standard Russian.

Yes. That is also grammatical and natural.

These versions are all possible:

• Сегодня сильно дует ветер
• Сегодня ветер сильно дует
• Ветер сегодня сильно дует

The difference is mainly emphasis and rhythm, not basic meaning.

• Сегодня сильно дует ветер sounds a bit more descriptive and flowing
• Сегодня ветер сильно дует highlights ветер a little more clearly as the subject

Russian allows this kind of variation much more than English.

Ветер is in the nominative case because it is the subject of the verb дует.

Dictionary form:

• ветер = wind

In this sentence:

• ветер дует = the wind blows

Since it is the subject, no case change is needed.

Because the sentence has two clauses:

1. Сегодня сильно дует ветер
2. поэтому я возьму тёплый шарф

Поэтому means therefore / so / that’s why, and it connects the result to the first clause.

So the comma separates:

• the reason/situation
• the consequence/result

This is standard punctuation in Russian.

This is a very common point of confusion.

• поэтому = therefore / so / that’s why
• потому что = because

In your sentence:

• Сегодня сильно дует ветер, поэтому я возьму тёплый шарф.
• Today it’s very windy, so I’ll take a warm scarf.

If you used потому что, the structure would change:

• Я возьму тёплый шарф, потому что сегодня сильно дует ветер.
• I’ll take a warm scarf because it’s very windy today.

So:

• поэтому introduces the result
• потому что introduces the reason

Возьму is the simple future of the perfective verb взять (to take).

Russian uses:

• perfective future for a single completed action in the future
• imperfective future (буду брать) for an ongoing, repeated, or process-like action

Here the speaker means one complete action:

• I’ll take a warm scarf

So возьму is the natural choice.

Compare:

• Я возьму шарф. = I’ll take a scarf.
  one completed act

• Я буду брать шарф каждый день. = I’ll be taking a scarf every day.
  repeated/habitual

It actually is in the accusative case, but for a masculine inanimate noun like шарф, the accusative looks the same as the nominative.

So:

• nominative: шарф
• accusative: шарф

That is why there is no visible change.

Compare with an animate masculine noun:

• Я вижу брата = I see my brother
• nominative: брат
• accusative: брата

But:

• Я возьму шарф
• nominative: шарф
• accusative: шарф

Because тёплый agrees with шарф.

Here шарф is:

• masculine
• singular
• inanimate
• accusative

For masculine inanimate nouns, the accusative adjective form is the same as the nominative form:

• тёплый шарф
  nominative
• возьму тёплый шарф
  accusative, but same-looking form

So both words match correctly:

• тёплый = masculine singular inanimate accusative/nominative form
• шарф = masculine singular inanimate accusative/nominative form

Yes, absolutely.

Russian often omits subject pronouns when the meaning is clear from the verb ending.

So both are possible:

• ... поэтому я возьму тёплый шарф
• ... поэтому возьму тёплый шарф

Since возьму already means I will take, the я is not strictly necessary.

Including я can:

• make the sentence a little clearer
• add slight emphasis to the speaker

The main stresses are:

• сегóдня
• сúльно
• ду́ет
• вéтер
• поэтому
• возьму́
• тёплый
• шарф

The letter ё always indicates stress, so тёплый is definitely pronounced with yo:

• TYOP-lyy

In many printed texts, ё is often written as е, so you may see:

• теплый

But the pronunciation is still тёплый, not теплый with a plain e sound.

Grammatically, it is closer to:

• The wind is blowing strongly today

But in natural English, the usual translation is often:

• It’s very windy today

So the Russian structure is more literal, while the English translation may sound more idiomatic.

That is very common when talking about weather between Russian and English.