Learn Hardcore Croatian: Danas je vjetar slabiji nego jučer. - Today the wind is weaker than yesterday.

Context tells you which English article you would use. Here, because we are talking about today’s wind vs yesterday’s wind, English uses the wind, but Croatian just uses vjetar.

Why is the verb je in second position (after Danas) and not right before vjetar, like Danas vjetar je slabiji?

In standard Croatian, short forms of the verb biti (to be) like je behave like clitics: they normally go in second position in the clause, after the first stressed word or phrase.

So:

Danas je vjetar slabiji nego jučer. ✅ (natural)
Vjetar je danas slabiji nego jučer. ✅ (also natural; now vjetar is first)
Danas vjetar je slabiji nego jučer. ❌ (sounds wrong in standard Croatian)

The rule is often called the second‑position clitic rule. In practice, when you start a sentence, you usually put one word/phrase first (here Danas or Vjetar), and then the short verb je comes immediately after that.

What form is slabiji, and how is it formed from slab?

Slabiji is the comparative form of the adjective slab (weak).

slab – weak
slabiji – weaker (more weak)

Formation:

base adjective: slab
add the comparative suffix -iji → slab + iji = slabiji

It also agrees with vjetar in:

gender: masculine
number: singular
case: nominative

So for different genders you’d say:

vjetar je slabiji (masculine: wind is weaker)
rijeka je slabija (feminine: the river is weaker / has less current)
more je slabije (neuter: the sea is weaker = less rough)

Why do we use nego and not od in slabiji nego jučer?

Both nego and od can be used in comparisons, but in standard grammar they are used a bit differently:

nego is used when the second part of the comparison is in the same case or is a whole clause, e.g.
- slabiji nego jučer – weaker than yesterday
- slabiji nego ti – weaker than you
- slabiji nego što je bio jučer – weaker than he was yesterday
od is used when the second part is typically in the genitive:
- slabiji od jučerašnjeg vjetra – weaker than yesterday’s wind
- slabiji od tebe – weaker than you (genitive tebe)

In everyday speech, many people mix them more freely, but in standard Croatian:

slabiji nego jučer is the preferred form.

What part of speech are danas and jučer? Do they change form?

Danas and jučer are adverbs of time:

danas – today
jučer – yesterday

As adverbs, they do not decline (they don’t change for case, gender, or number). They stay the same in all contexts:

Danas je hladno. – It is cold today.
Vidjeli smo se jučer. – We saw each other yesterday.
Ne radim danas, nego jučer. (artificial example) – I’m not working today, but (I did) yesterday.

They always keep their form danas, jučer.

Can I say Danas vjetar je slabiji nego jučer or Vjetar danas je slabiji nego jučer?

In standard Croatian, these are not natural because of the position of je:

Danas je vjetar slabiji nego jučer. ✅
Vjetar je danas slabiji nego jučer. ✅

But:

Danas vjetar je slabiji nego jučer. ❌
Vjetar danas je slabiji nego jučer. ❌

The verb je as a clitic wants to be in the second position in the sentence or clause. In those incorrect versions, it ends up in 3rd position, which sounds wrong to native speakers in standard language.

Why is vjetar in the nominative case here? Could it ever be in another case?

In this sentence, vjetar is the subject of the verb je (is), so it is in the nominative singular masculine:

vjetar – (the) wind (subject)

If you used vjetar in a different role, the case would change:

Vidim vjetar. – I see the wind. (accusative: same form, but function is object)
Bojim se vjetra. – I am afraid of the wind. (genitive: vjetra)
O vjetru pričamo. – We are talking about the wind. (locative: vjetru)

Here, because it is the subject of is, nominative is required: vjetar je slabiji.

Can I drop the verb and just say Danas vjetar slabiji nego jučer?

In normal, complete sentences, you should not drop je here. You need je to say is:

Danas je vjetar slabiji nego jučer. ✅

In headlines, notes, or very informal speech, Croatians sometimes omit je, especially in short descriptive phrases:

Danas vjetar slabiji nego jučer. (could appear as a note or weather headline)

But as a learner, for full sentences, it’s safer and more correct to keep the verb:

always say: Danas je vjetar slabiji nego jučer.

How do I pronounce jučer, and what is the difference between č and ć?

Jučer is pronounced approximately:

ju – like you
č – like ch in church
er – like air but shorter (Croatian r is tapped)

Roughly: YOO-cher (with a rolled/tapped r).

Difference between č and ć:

č – a harder, stronger ch sound (like in English church).
ć – a softer, more palatal sound, somewhat like a soft tch.

In jučer, the letter is č (the harder one). Spelling with ć (jućer) would be wrong in standard Croatian.

Is there any nuance in meaning between slabiji vjetar and something like manje jak vjetar?

Both can describe weaker wind, but they differ in style:

slabiji vjetar – natural, compact, the normal way to say weaker wind.
manje jak vjetar – literally less strong wind. It is grammatically correct but sounds a bit more analytical and less idiomatic in this context.

For simple comparisons of strength, Croatians usually prefer the comparative form:

Danas je vjetar slabiji nego jučer. ✅ (most natural)
Danas je vjetar manje jak nego jučer. 😐 (understandable but less natural in everyday speech)