Március meleg.

Because Hungarian usually leaves out the verb to be in the present tense when the subject is third person and the predicate is a noun or adjective.

So:

• Március meleg. = March is warm.
• literally, it looks like March warm.

This is completely normal in Hungarian.

Compare:

• Én meleg vagyok. = I am warm.
• Te meleg vagy. = You are warm.
• Március meleg. = March is warm.

In the past or future, the verb appears again:

• Március meleg volt. = March was warm.

Most directly, it means March is warm.

That is slightly different from It is warm in March:

• Március meleg. = you are describing March itself.
• Márciusban meleg van. = It is warm in March.

So if you mean the weather during the month, Márciusban meleg van is often the more natural everyday way to say it.

Because Március and márciusban do different jobs.

• Március = March as the subject
• márciusban = in March

The ending -ban / -ben means in.

So:

• Március meleg. = March is warm.
• Márciusban meleg van. = It is warm in March.

English often uses in March, but Hungarian can either make March the subject or use the -ban/-ben ending, depending on the exact meaning.

That’s right: in Hungarian, month names are normally written with a lowercase letter.

So normally you write:

• március
• április
• május

In this sentence, Március is capitalized only because it is the first word of the sentence.

If it appeared in the middle of a sentence, it would usually be:

• Azt mondta, hogy március meleg.

Because month names usually behave like proper names and do not need an article in this kind of sentence.

So:

• Március meleg. = natural
• A március meleg. = possible only in a more specific or contrastive context, such as this particular March

For example:

• Az idei március meleg. = This year’s March is warm.

But as a simple general statement, no article is the normal choice.

Here, meleg is an adjective meaning warm.

It is the predicate adjective of the sentence:

• Március = subject
• meleg = predicate adjective

So the structure is basically:

• March + warm

Hungarian does not need a separate word for is here in the present tense.

Yes, meleg can cover both warm and sometimes hot, depending on context.

For weather, it often means:

• warm
• mildly hot
• pleasantly warm, or just hot, depending on the situation

So Március meleg would usually be understood as March is warm, not March is hot, unless the context suggests unusually high temperatures.

Yes, but it means something different.

• Március meleg. = March is warm.
  This is a full sentence.
• meleg március = a warm March
  This is just a noun phrase, not a complete sentence.

So word order changes the function:

• adjective + noun = a noun phrase
• noun + adjective here = a sentence with a predicate adjective

It is grammatical, but by itself it can sound a bit short, general, or headline-like.

A Hungarian speaker might more often say something like:

• Márciusban meleg van.
• A március meleg szokott lenni. = March tends to be warm.
• Meleg a március. = a more marked version, depending on emphasis

So Március meleg is understandable and correct, but in everyday speech another wording may sound more natural depending on what exactly you want to say.

A simple English-friendly approximation is:

• Március ≈ MAAR-tsee-oosh
• meleg ≈ MEH-leg

A few helpful points:

• stress is on the first syllable in both words
• á is a long a
• c in március sounds like ts
• the g in meleg is a hard g, like in go

So the whole sentence is roughly:

• MAAR-tsee-oosh MEH-leg

No. Hungarian has no grammatical gender like he/she nouns in many Indo-European languages, and adjectives do not agree the way they do in languages such as French, German, or Spanish.

So meleg stays meleg.

That means a learner does not need to worry about masculine/feminine adjective forms here. This is one reason Hungarian sentences like Március meleg can look very simple on the surface.