Когда станет не так пасмурно, я надену майку, шорты и пойду гулять.

Станет is the future of стать, which means to become.

So:

• станет пасмурно = it will become cloudy
• станет не так пасмурно = it will become less cloudy / not so cloudy

If you used будет, the meaning would lean more toward it will be, not it will become. Russian often uses стать when talking about a change of state.

So the sentence is about a change in the weather, not just a future description of it.

Because пасмурно is the form Russian commonly uses in impersonal weather expressions.

Compare:

• Сегодня пасмурно. = It’s cloudy today.
• День пасмурный. = The day is cloudy.

In your sentence, there is no noun like день or небо being described. It is just a general statement about the weather, so Russian uses пасмурно.

This is very common:

• холодно = cold
• жарко = hot
• темно = dark
• светло = light

These often function like it is ... in English.

Literally, it means not so cloudy or not that cloudy.

In natural English, depending on context, it can mean:

• not so cloudy
• less cloudy
• not as gloomy/cloudy

Here, так means something like so / that much / to that degree.

So:

• пасмурно = cloudy
• так пасмурно = so cloudy
• не так пасмурно = not so cloudy

This is a very common Russian pattern:

• не так холодно = not so cold
• не так трудно = not so difficult
• не так далеко = not so far

This is a major difference between English and Russian.

In English, after when, if, as soon as, and similar words, we often use the present tense to refer to the future:

• When it gets warmer, I’ll go out.

But in Russian, when the meaning is future, Russian normally uses a future form:

• Когда станет теплее, я выйду.

So in your sentence:

• Когда станет не так пасмурно... = When it becomes / gets less cloudy...

This is completely normal Russian grammar. English and Russian just handle future time in subordinate clauses differently.

Because Когда станет не так пасмурно is a subordinate clause.

Russian normally separates subordinate clauses with commas:

• Когда станет не так пасмурно, я надену майку...

This is like:

• When it gets less cloudy, I’ll put on a tank top...

The comma is required in standard Russian spelling.

This is a very common learner question.

In standard Russian:

• надеть = to put on an item of clothing
• одеть = to dress a person

So:

• Я надену майку. = I will put on a tank top.
• Я одену ребёнка. = I will dress the child.

A classic memory trick is:

• надеть что
• одеть кого

So here, because the speaker is putting on clothes, надену is the correct verb.

Because they are the direct objects of надену, so they are in the accusative case.

майка → майку

Майка is feminine singular, so its accusative form changes:

• nominative: майка
• accusative: майку

шорты

Шорты is plural. Since it refers to inanimate things, its accusative plural is the same as the nominative plural:

• nominative: шорты
• accusative: шорты

So:

• надену майку
• надену шорты

are both correct.

Because the subject is still the same: я.

Russian often omits repeated subjects when it is already clear who is doing the action.

So:

• я надену майку, шорты и пойду гулять

means:

• I’ll put on a tank top, shorts, and go for a walk

You could repeat я, but it would usually sound unnecessary here.

Пойду гулять literally means I will go to walk or I’ll go out for a walk.

This uses:

• пойду = future of пойти (to go, to set off)
• гулять = to walk / stroll / spend time outdoors

Together, пойти + infinitive often means to go and do something or to set off to do something.

So:

• пойду гулять = I’ll go for a walk / I’ll go out walking

By contrast:

• буду гулять = I will be walking / I’ll be out walking

That focuses more on the activity itself, not on the act of setting off. In your sentence, пойду гулять fits better because the speaker is talking about what they will do once the weather improves.

It can be broader.

Гулять often means:

• to walk
• to stroll
• to go out
• to spend time outside
• to take a walk

So пойду гулять does not always mean a serious, purposeful walk. It can simply mean I’ll go outside for a bit or I’ll go for a stroll.

That is why it is very common in everyday speech.

Yes. The sentence gives a natural sequence of actions:

1. the weather gets less cloudy
2. the speaker puts on light clothes
3. the speaker goes for a walk

So the order matches the real-life order.

Russian word order is flexible, but this version sounds very natural because it presents events step by step.

Yes, Russian word order is flexible, but changing it changes emphasis.

For example:

• Когда станет не так пасмурно, я надену майку, шорты и пойду гулять.
  Neutral, natural order.

You could also say:

• Я пойду гулять, когда станет не так пасмурно.
  This puts more focus on I’ll go for a walk.

Or:

• Когда станет не так пасмурно, я пойду гулять и надену майку и шорты.
  Grammatically possible, but less natural because the order of actions feels less logical.

So the original sentence is a very natural way to say it.

Because Russian often uses impersonal constructions for weather and general conditions.

English needs it:

• When it gets less cloudy...

Russian does not:

• Когда станет не так пасмурно...

There is no real subject here. Russian simply states the change in the condition.

This happens a lot with weather and environment:

• Темнеет. = It’s getting dark.
• Холодает. = It’s getting colder.
• Стало тепло. = It became warm.

So the absence of it is completely normal.

Usually майка means a sleeveless shirt or undershirt, often translated as:

• tank top
• sleeveless shirt
• sometimes undershirt

The exact English translation depends on context. In this sentence, since the person is dressing for nicer weather, tank top or T-shirt-like sleeveless top is a good natural interpretation.

So if you already know the overall meaning, майка here suggests light, casual summer clothing.