Learn Hardcore Korean: ama oneureun biga an ol geoya.

아마: an adverb meaning “probably/perhaps,” expressing likelihood.
오늘은: 오늘 (today) + topic marker 은; “as for today / today (contrasted).”
비가: 비 (rain) + subject marker 가; “rain” is the grammatical subject.
안: adverbial negation “not.”
올: the verb 오다 (to come) in the prospective/attributive form -ㄹ → 올.
거야: contraction of 것이야 (“it is a thing”), part of the periphrastic future -(으)ㄹ 거야 (“will/going to”), with a casual ending.

So it literally maps to “Probably, as for today, rain not will-thing be (casual).”

Why is the topic marker -은 on 오늘? Could I just say 오늘 or use 오늘이?

오늘은 marks “today” as the topic and often carries a contrastive nuance: “Today (as opposed to other days) …”
You can simply say 오늘 비가 안 올 거야 (dropping the particle) in casual speech; it’s neutral and common.
오늘이 is not used here because “today” isn’t the subject of “coming”; 비(가) is the subject of 오다. You’d only use 오늘이 if “today” were the subject of a different predicate (e.g., 오늘이 좋은 날이야 “Today is a good day”).

Why is it 비가 오다 (“rain comes”) instead of “it rains”?

Korean doesn’t use a dummy subject like English “it.” Weather nouns typically act as subjects:

Why is the negation placed as 안 올 and not somewhere else?

안 is an adverb that directly negates the verb phrase, so it goes immediately before the main verb stem:

Correct: 비가 안 올 거야
Incorrect: ❌ 비가 올 안 거야 (you can’t split 올 from 거야 and put 안 there) If you use the longer negative form -지 않다, it becomes 비가 오지 않을 거야.

What exactly is 올?

It’s the prospective/attributive form of 오다 formed with -ㄹ/을:

오다 → stem 오-
- -ㄹ → 올 It links to 거야/거예요/것이다 to create the periphrastic future (-(으)ㄹ 거- = “will / be going to”).

What is 거야 doing here?

거야 is a contraction of 것이야 (“it is a thing”). Together with -ㄹ, it builds the future:

오다 → 올 거야 = “(I think) it will come / it’s going to come.” It’s a casual, non-honorific sentence ending. Polite versions appear below.

How do I say this more politely or more formally?

Polite: 아마 오늘은 비가 안 올 거예요.
Formal: 아마 오늘은 비가 오지 않을 겁니다. or …않을 것입니다.
Written/plain explanatory: 아마 오늘은 비가 오지 않을 것이다. If you want to hedge more, you can use:
아마 오늘은 비가 안 올 것 같아요. (“I think it probably won’t rain.”)

What’s the nuance difference between 안 올 거야, 안 오겠지, and 안 올 것 같아?

안 올 거야: More assertive/forecast-like. Speaker sounds fairly confident.
안 오겠지: Uses -겠- (conjecture). Softer, speculative: “I suppose it won’t rain.”
안 올 것 같아: Explicitly hedged as a personal guess: “I think it won’t rain.” Often feels even softer than -겠지 in tone.

Do 아마 and 아마도 differ? Where can I place 아마?

아마 and 아마도 both mean “probably/perhaps.” 아마도 can feel slightly more emphatic or formal/written, but in speech they’re largely interchangeable.
Placement is flexible:
- 아마 오늘은 비가 안 올 거야.
- 오늘은 아마 비가 안 올 거야. Both are natural. Keeping 아마 early in the clause is typical.

Can I move the words around more? Which orders are natural?

Natural options include:

아마 오늘은 비가 안 올 거야.
오늘은 아마 비가 안 올 거야.
Without the topic marker: 아마 오늘 비가 안 올 거야. To strongly contrast “today,” you can also do:
비가 오늘은 안 올 거야. (emphasizes “as for today”) Over-scrambling can sound unnatural, so prefer the patterns above.

Can I drop particles in casual speech?

Yes, very common in conversation:

오늘 비 안 올 거야.
비 안 올 거야. Context supplies the missing roles. Keep particles when you need clarity or want to show contrast.

What does it mean if I say 오늘은 비는 안 올 거야?

Topicalizing 비 with -는 adds contrast: “As for rain, it won’t come today (but maybe something else—like snow—might).”

Is 오다 → 올 irregular?

No. It’s regular:

Any pronunciation tips or common sound changes here?

오늘은 often sounds like [오느른].
안 올 links to [아놀] (the final ㄴ carries over to the vowel-initial 올).
올 거야 is pronounced [올 꺼야] due to tensification (된소리되기) of 거 after l/r (ㄹ). Saying it smoothly: [아마 오느른 비가 아놀 꺼야].

How should I space 올 거야? I often see 올거야 online.

Standard spelling requires a space: 올 거야 (because 거 comes from the noun 것). Writing 올거야 is common informally online but is nonstandard.

Could I use 못 instead of 안 here?

No. 못 expresses inability (“cannot”), which doesn’t fit weather phenomena. Use 안 or -지 않다 for simple negation:

Is 비가 내리다 different from 비가 오다?

Both are natural for “it rains.” Subtle nuance:

비가 오다: default everyday choice.
비가 내리다: literally “rain falls,” sometimes a bit more descriptive or literary. In forecasts/news, both appear.

How would I ask or soften this statement?

Asking: 오늘은 비가 안 올까요? (“Do you think it won’t rain today?”) or positively, 오늘 비가 올까요?
Soften as a guess: 아마 오늘은 비가 안 오겠죠. (polite, conjectural)
Hedge with personal stance: 아마 오늘은 비가 안 올 것 같아요.