Learn Hardcore Hungarian: Nyáron gyakrabban futok a parkban, télen ritkábban, mert lassú vagyok. - In summer I run in the park more often; in winter less often because I am slow.

In Hungarian, names of seasons used as general time expressions normally appear without an article, and very often with a case ending that turns them into adverbs of time.

Nyáron literally comes from nyár (summer) + -on and means in (the) summer / during summer.
Télen is tél (winter) + -en, meaning in (the) winter.

When you talk about something that happens generally, habitually in a certain season, you say:

Nyáron sokat utazom. – I travel a lot in (the) summer.
Télen korán sötétedik. – It gets dark early in (the) winter.

You’d only use an article if the season is made specific in some way, for example:

Ebben a nyárban nem volt túl meleg. – In this summer it wasn’t very warm.

So in your sentence Nyáron is perfectly normal without any article.

What exactly is the -on / -en ending in Nyáron and télen?

Historically, -on / -en / -ön is the superessive case, meaning on / on top of:

asztal (table) → az asztalon – on the table
padló (floor) → a padlón – on the floor

With time words, this same ending has developed a purely temporal meaning: in / during / on (a certain time):

Nyáron – in summer
Télen – in winter
Ősszel – in autumn
Hétfőn – on Monday
Reggel – in the morning (this one has fossilised without the full ending)

So Nyáron gyakrabban futok… literally is something like “On summer I run more often…”, but idiomatically it means “In summer I run more often…”.

What do gyakrabban and ritkábban mean, and how are they formed from gyakran and ritkán?

gyakran = often
ritkán = rarely / seldom

Their comparative forms are:

gyakrabban = more often
ritkábban = less often / more rarely

Hungarian generally forms the comparative of adjectives and adverbs by adding -bb, often with a bit of vowel adjustment:

gyors → gyorsabb – fast → faster
gyorsan → gyorsabban – quickly → more quickly
lassú → lassabb – slow → slower
lassan → lassabban – slowly → more slowly
gyakran → gyakrabban – often → more often
ritkán → ritkábban – rarely → more rarely / less often

So in your sentence:

gyakrabban futok – I run more often
ritkábban (futok) – I run less often

Why is it futok and not futom? What’s the difference?

Hungarian verbs have two conjugations:

indefinite conjugation: used when there is no definite direct object (or no object at all)
definite conjugation: used when there is a definite direct object (this, that, it, him, her, the X, etc.)

Futni (to run) is usually intransitive here (no direct object: you are just running). So you use the indefinite form:

futok – I run / I am running (no object)

Futom would mean “I run it”, implying some definite object:

Futom a távot. – I run the distance.
Futom a maratont. – I run the marathon.

In your sentence there is no such object, so futok is correct:

Nyáron gyakrabban futok a parkban… – In summer I run more often in the park…

What does a parkban mean, and what is the -ban ending?

park = park
a park = the park
a parkban = in the park

The ending -ban / -ben is the inessive case, meaning in / inside:

ház → a házban – in the house
autó → az autóban – in the car
park → a parkban – in the park

The choice -ban vs -ben depends on vowel harmony and consonant environment; park takes -ban.

So futok a parkban literally is “I run in the park”.

Is the word order fixed? Can I also say Gyakrabban futok a parkban nyáron?

Hungarian word order is flexible, but it’s not random: it reflects topic–focus and what is being emphasized.

Your original sentence:

Nyáron gyakrabban futok a parkban…

Here,

Nyáron is a time expression at the beginning, giving context: As for summer…
gyakrabban is before the verb, but not in a strong focus position; the whole clause just describes a typical situation in summer.

You could say, for example:

Gyakrabban futok a parkban nyáron.
– Sounds like neutral information, slightly emphasizing gyakrabban (more often), with nyáron just specifying when.
A parkban futok gyakrabban nyáron.
– Now you emphasize a parkban: It’s in the park that I run more often in summer (not somewhere else).
Nyáron a parkban futok gyakrabban.
– Emphasis on a parkban again, within the summer context.

All are grammatically fine, but the most natural neutral version for a general habitual statement is very close to what you already have: Nyáron gyakrabban futok a parkban…

After télen ritkábban there is no verb. Is something omitted? Is that normal?

Yes, Hungarian often omits repeated material that can be easily understood from context. Here the full version would be:

Nyáron gyakrabban futok a parkban, télen ritkábban futok a parkban, mert lassú vagyok.

Because futok a parkban is exactly the same in both parts, it is naturally dropped in the second:

Nyáron gyakrabban futok a parkban, télen ritkábban, mert lassú vagyok.

Speakers immediately understand that ritkábban refers to running in the park in winter.

This kind of ellipsis is very common and sounds natural.

Why do we say mert lassú vagyok with vagyok? I thought the verb to be is often omitted in Hungarian.

You’re right that “to be” (lenni) is often left out in the present tense, but only in the 3rd person:

Ő lassú. – He/She is slow.
A park nagy. – The park is big.
(No van.)

In 1st and 2nd person you must use the form of lenni:

Én lassú vagyok. – I am slow.
Te lassú vagy. – You are slow.
Mi lassúak vagyunk. – We are slow.

So in your sentence:

mert lassú vagyok = because I am slow

Leaving out vagyok (mert lassú) would be ungrammatical in standard Hungarian.

Could I also say mert lassan futok instead of mert lassú vagyok? What’s the difference between lassú and lassan here?

Yes, both are possible, but they express the idea slightly differently:

lassú = slow (adjective)
lassan = slowly (adverb)

mert lassú vagyok – because I am slow
- This describes you as a slow runner/person in general.
mert lassan futok – because I run slowly
- This describes the manner of your running specifically.

In context of running frequency:

mert lassan futok connects more directly to the activity of running.
mert lassú vagyok feels more like a general self-description (I’m slow, that’s why I don’t run so often).

Both are grammatically correct; choice depends on what nuance you want.

Why is there a comma before mert in …, mert lassú vagyok?

Mert introduces a subordinate clause of reason (a “because”-clause). In Hungarian, when this reason clause comes after the main clause, you normally separate them with a comma:

Nem megyek futni, mert fáradt vagyok.
– I’m not going running because I’m tired.

Your sentence follows the same rule:

Nyáron gyakrabban futok a parkban, télen ritkábban, mert lassú vagyok.

Punctuation breakdown:

Comma after parkban: separates two related clauses (Nyáron… vs Télen…).
Comma after ritkábban: separates the winter-part from the mert-clause.
mert lassú vagyok is the reason for what was said before, so it’s introduced by mert and preceded by a comma.

This mirrors English usage quite closely:
“… less often in winter, because I am slow.”