Learn Hardcore Finnish: Joulukuu on kuukausi, jolloin odotan joulua. - December is the month when I wait for Christmas.

Jolloin is a relative adverb that literally means something like “at which time / when” and it refers back to a noun of time (here: kuukausi, “month”).

So:

Joulukuu on kuukausi, jolloin odotan joulua.
= “December is the month when I wait for Christmas.”

In English, when can act both as a conjunction (“when I came home…”) and as a relative word (“the time when I came…”).
In Finnish:

kun is mainly used as a conjunction:
- Odotan joulua, kun on joulukuu. – “I wait for Christmas when it’s December.”
jolloin is used like relative when/at which (time) referring back to a time word:
- kuukausi, jolloin… – “the month when…”
- päivä, jolloin… – “the day when…”

So jolloin is chosen because it ties the clause odotan joulua specifically to kuukausi as a defining relative clause: “the month during which I wait for Christmas.”

Why is there a comma before jolloin?

In Finnish, a comma is almost always used before a subordinate clause, including relative clauses like this one.

Joulukuu on kuukausi, jolloin odotan joulua.
- Main clause: Joulukuu on kuukausi (“December is a month”)
- Subordinate (relative) clause: jolloin odotan joulua (“when I wait for Christmas”)

Because jolloin odotan joulua depends on and describes kuukausi, Finnish punctuation rules require a comma before jolloin.

You must write the comma here in standard written Finnish; leaving it out would be considered incorrect in formal writing.

Why is it odotan joulua and not odotan joulu or odotan joulun?

The verb odottaa (“to wait for, expect”) normally takes its object in the partitive case, not in basic nominative or genitive:

odotan joulua – “I am waiting for Christmas”
- joulu → joulua (partitive singular)

In Finnish, some verbs always or almost always require the partitive object because of their meaning or usage pattern. Odottaa is one of them, so:

odotan sinua – I’m waiting for you
odotan bussia – I’m waiting for the bus
odotan lomaa – I’m waiting for the vacation
odotan joulua – I’m waiting for Christmas

Saying odotan joulu is ungrammatical.
Odotan joulun is possible but means something different, more like “I expect Christmas (to do something / to bring something)” and sounds unusual; in the sense of literally waiting for the holiday to come, Finns say odotan joulua.

What is the structure and meaning of Joulukuu as a word?

Joulukuu is a compound word:

joulu = Christmas
kuu = moon; but in calendar words it means “month”

So literally, joulukuu is “Christmas month” – the month associated with Christmas. This is the Finnish word for December.

Other months are formed similarly, for example:

helmikuu – February (literally “pearl month”)
kesäkuu – June (“summer month”)
syyskuu – September (“autumn month”)

Why is Joulukuu capitalized here if Finnish month names are usually not capitalized?

Finnish month names are normally written with a lowercase letter:

joulukuu – December
tammikuu – January

However, the first word of a sentence is always capitalized, no matter what it is. In this sentence, joulukuu is the first word, so it appears as Joulukuu.

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

Pidän eniten joulukuusta. – “I like December the most.”

Could I say Joulukuu on se kuukausi, jolloin odotan joulua? What is the difference?

Yes, you can say:

Joulukuu on se kuukausi, jolloin odotan joulua.

The meaning is basically the same, but the nuance shifts slightly:

Joulukuu on kuukausi, jolloin odotan joulua.
– “December is a month when I wait for Christmas.”
Neutral statement; in practice, it implies the month when this happens, because context usually makes that clear.
Joulukuu on se kuukausi, jolloin odotan joulua.
– “December is the month when I wait for Christmas.”
The little word se adds emphasis, like English the with a bit of pointing: that very month.

So se works like a demonstrative (“that/the”) which makes the identification stronger or more contrastive. Both versions are grammatically correct.

Is jolloin always used with time words like kuukausi, päivä, etc.?

Jolloin is typically used when:

There is a head noun that refers to a time or event, and
You want to express “when / at which (time)” relative to that noun.

Common patterns:

päivä, jolloin… – the day when…
hetki, jolloin… – the moment when…
vuosi, jolloin… – the year when…
juhla, jolloin… – the celebration when…

But jolloin can also be used a bit more abstractly for situations, not only literal clock time, as long as the idea is “at which time / on which occasion”.

If you are not referring back to a specific noun of time or occasion, you usually use other words:

kun – when (as a conjunction)
milloin – when (as a question word)

What is the basic form and case of kuukausi in this sentence?

In the sentence:

Joulukuu on kuukausi, jolloin odotan joulua.

Kuukausi is:

in its basic (nominative) singular form: kuukausi
functioning as a predicate noun after the verb on (“is”)

Structure:

Joulukuu (subject, nominative)
on (3rd person singular of olla, “to be”)
kuukausi (predicate noun / complement, nominative)

So it’s the classic A is B structure: A on B.

Why is odotan used, and what form is it?

Odotan is the first person singular present indicative form of the verb odottaa (“to wait for, expect”).

Conjugation of odottaa (present tense):

minä odotan – I wait / I am waiting
sinä odotat – you wait
hän odottaa – he/she waits
me odotamme – we wait
te odotatte – you (pl.) wait
he odottavat – they wait

So odotan here simply means “I (habitually) wait / I am waiting”. In Finnish, the present tense covers both English simple present (“I wait”) and present continuous (“I am waiting”), and which translation you choose depends on context.

Could the sentence be reordered, like Kuukausi, jolloin odotan joulua, on joulukuu? Is that still natural?

Yes, this word order is grammatically correct and understandable:

Kuukausi, jolloin odotan joulua, on joulukuu.

Meaning: “The month when I wait for Christmas is December.”

Differences:

Original: Joulukuu on kuukausi, jolloin odotan joulua.
– more natural and straightforward; starts with what you’re defining (Joulukuu).
Reordered: Kuukausi, jolloin odotan joulua, on joulukuu.
– puts focus first on the description (“the month when I wait for Christmas”) and then reveals that this month is joulukuu.

The original word order is more typical in everyday speech, but the alternative is not wrong and can appear in writing for emphasis or stylistic reasons.

How would you say this more simply without the relative clause?

You can express a similar idea with a simpler structure, for example:

Joulukuussa odotan joulua.
– “In December I wait for Christmas.”

Here:

joulukuussa is the inessive case of joulukuu (“in December”).
The meaning is close, though the original sentence explicitly says “December is the month when…”, which is a bit more descriptive or explanatory.