Pogoda może się szybko zmienić.

• pogoda = the subject, weather
• może = can / may, the 3rd person singular present form of móc (to be able to / can)
• się = a reflexive marker used with the verb here
• szybko = quickly
• zmienić = infinitive, to change

So the structure is basically:

subject + modal verb + się + adverb + infinitive

That is very normal in Polish.

Może is the present-tense, 3rd person singular form of móc.

Because pogoda is singular, Polish uses singular może:

• ja mogę = I can
• ty możesz = you can
• on / ona / ono może = he / she / it can

Since pogoda is grammatically singular, you get pogoda może.

In this sentence, może works like English can or may.

Because the natural Polish verb here is zmienić się, not just zmienić.

There is an important difference:

• zmienić coś = to change something
• zmienić się = to change, to become different

So:

• Zmieniłem plan = I changed the plan.
• Plan się zmienił = The plan changed.

In your sentence, the weather is not changing something else; the weather itself changes. That is why się is required.

Not always. Sometimes English learners want to translate się word-for-word as oneself / itself, but that often does not work well.

In many Polish verbs, się is just part of how the verb functions. Here, zmienić się means to change in the sense of undergo a change.

So in this sentence, it is better to understand się as part of the verb pattern, not as a separate word meaning itself.

Because after może, Polish normally uses an infinitive.

This is parallel to English:

• The weather can change
• Pogoda może się zmienić

You do not say a second fully conjugated verb after może here. The modal verb is conjugated, and the next verb stays in the infinitive.

This is a question of aspect, which is very important in Polish.

• zmienić się = perfective
• zmieniać się = imperfective

In this sentence, zmienić się suggests a change happening as a whole event: the weather may change quickly.

If you said Pogoda może się szybko zmieniać, that would usually suggest something more ongoing, repeated, or habitual, such as the weather can be changing quickly or can change quickly from time to time / in a fluctuating way.

For a simple statement about the possibility of a change occurring, zmienić się is the more natural choice.

Yes, może can also mean maybe / perhaps in some contexts.

But here it is clearly the verb może from móc, because:

• it follows the subject pogoda
• it is followed by an infinitive: zmienić
• the sentence has normal subject + verb structure

Compare:

• Może pójdę jutro. = Maybe I’ll go tomorrow.
• Pogoda może się zmienić. = The weather can/may change.

So in your sentence, może is definitely the verb, not the particle meaning maybe.

Because Polish does not have articles like English a / an / the.

So pogoda can mean:

• weather
• the weather

The exact meaning comes from context.

This is normal in Polish, and English speakers need time to get used to it.

Yes. Polish word order is more flexible than English word order.

Your sentence is completely natural:

• Pogoda może się szybko zmienić.

But you may also hear:

• Pogoda może szybko się zmienić.

Both are natural. The difference is mostly about rhythm, emphasis, and style, not basic meaning.

Polish often moves small words like się around more freely than English would allow, though there are still preferences.

Się is a clitic, which means it is a small unstressed word that does not usually stand at the very beginning of a clause.

In neutral sentences, it often comes near the verb:

• Pogoda może się zmienić.
• Pogoda może szybko się zmienić.

Both are fine.

A good learner rule is: put się after the conjugated verb unless you have a reason to place it elsewhere.

That rule will sound natural in many everyday sentences.

Yes, pogoda is a feminine noun.

You can see that in dictionary form and in endings in other contexts. But in the present tense, the verb form może does not show gender. It only shows person and number.

So even though pogoda is feminine, you still get:

• pogoda może
• kobieta może
• książka może

All singular subjects use może in the 3rd person singular present.

Gender becomes more visible in the past tense, for example:

• Pogoda się zmieniła. = The weather changed.

The ending -ła shows feminine singular.

In careful pronunciation, się is approximately like shyeng but very short and light, though that English approximation is imperfect.

A few key points:

• si before a vowel often sounds like a soft ś
• ę is a nasal vowel, though in real speech its pronunciation can vary by context

In normal speech, się is often pronounced less carefully than a dictionary-style form. Learners should mainly focus on recognizing it and using it naturally, rather than trying to force an exaggerated nasal sound.

A rough English approximation is ZMYEH-nyich, but that is only approximate.

Useful parts:

• zmi- begins with a zm cluster
• nie here sounds like a soft nye
• -ć is a soft consonant, somewhat like a very soft ch/tch sound, but not exactly English

The stress is on the second-to-last syllable:

ZME-nić

More exactly, Polish stress rules put it on mie.

Yes. In Polish, just like in English, a present-tense modal plus infinitive can refer to a present possibility or a future possibility.

So Pogoda może się szybko zmienić can mean that the weather is capable of changing quickly, or that it may change quickly from now/on soon. Context tells you which is intended.

That is completely normal usage.