Learn Hardcore Finnish: Kun sumu katoaa ja lämpötila nousee, tie näyttää heti turvallisemmalta. - When the fog disappears and the temperature rises, the road immediately looks safer.

Kun sumu katoaa… tie näyttää…
literally: When the fog disappears, the road looks…
but understood as: When the fog disappears, the road will look…

In time clauses with kun, the present tense can refer to:

present time: Kun sumu katoaa, tie näyttää heti turvallisemmalta (it’s happening now/regularly)
future time: Kun sumu katoaa, tie näyttää heti turvallisemmalta (later, when that happens)

You usually don’t use a separate future tense in Finnish (there basically isn’t one); context gives the time reference.

What is the basic form of katoaa, and why does it end in -aa?

The dictionary (infinitive) form is kadota = to disappear, to vanish.

kadota is a type 4 verb (ending in -ta/-tä).
In the 3rd person singular present, type 4 verbs drop -ta and lengthen the preceding vowel:
- kadota → kado-
  - a (present ending) → katoaa
    (it disappears)

Other examples of the same pattern:

pelata → pelaa (to play → s/he plays)
haluta → haluaa (to want → s/he wants)

So katoaa is simply “he/she/it disappears” or here, “the fog disappears”.

Why is it lämpötila nousee and not something like “on korkeampi” for “rises”?

Lämpötila nousee literally means “the temperature rises” (or goes up).

lämpötila = temperature
nousta = to rise, to go up
nousee = 3rd person singular present of nousta (rises)

You could say:

Lämpötila on korkeampi. = The temperature is higher.

But that just describes a state, not the change.
In the sentence given, we’re talking about what happens over time (fog disappearing, temperature rising), so nousee is more natural than on korkeampi.

Why is there a comma before tie näyttää heti turvallisemmalta?

Finnish uses a comma between a subordinate clause and the main clause.

Kun sumu katoaa ja lämpötila nousee,
→ this is a subordinate time clause introduced by kun.
tie näyttää heti turvallisemmalta.
→ this is the main clause.

The rule:
If a sentence starts with a subordinate clause (starting with kun, koska, vaikka, jos, etc.), you put a comma before the main clause.

So the comma here is grammatically required.

Why are sumu and tie in their basic form, not something like sumun or tien?

Sumu and tie are the subjects of their clauses, so they are in the nominative case (the basic dictionary form):

sumu katoaa = the fog disappears
→ sumu = nominative singular subject
tie näyttää… = the road looks…
→ tie = nominative singular subject

Forms like sumun, tien are genitives and would be used for possession or other functions (e.g. sumun tiheys “the density of the fog”, tien pinta “the road’s surface”), not for the subject in this kind of sentence.

What does heti mean, and why is it placed where it is?

Heti means “immediately, right away”.

tie näyttää heti turvallisemmalta
≈ the road immediately looks safer / the road looks safer right away.

Word order for adverbs like heti is fairly flexible, but this position is very natural:

Kun sumu katoaa…, tie näyttää heti turvallisemmalta.

Other possible positions:

Kun sumu katoaa…, tie heti näyttää turvallisemmalta. (possible, but less neutral)
Kun sumu katoaa…, tie näyttää turvallisemmalta heti. (sounds more marked/emphatic)

The given sentence puts heti just before the adjective phrase, which is probably the most neutral and common choice here.

Why is it turvallisemmalta and not just turvallisempi?

The base adjective is turvallinen = safe.

First, it’s put into the comparative:
- turvallinen → turvallisempi = safer
Then, because it follows the verb näyttää (to look, to seem), it takes the ablative case (-lta / -ltä ending):
- turvallisempi → turvallisemmalta

So the structure is:

tie näyttää turvallisemmalta
literally: the road looks from-safer
meaning: the road looks/seems safer.

The ablative (-lta/-ltä) is regularly used with verbs like näyttää and tuntua:

Näytät väsyneeltä. = You look tired.
Se tuntuu vaaralliselta. = It feels dangerous.

Why does turvallisempi become turvallisemmalta specifically (with -mm- and -lta)?

Step by step:

Base adjective
- turvallinen = safe
Comparative form
- comparative adds -mpi to the stem
- turvallinen → stem turvallise- → turvallisempi = safer
Case ending for “näyttää”
- with näyttää (“to look/seem”), the adjective normally goes into the ablative
- ablative ending is -lta/-ltä (depending on vowel harmony)
Combine comparative + ablative
- turvallisempi → stem turvallisemma- (gradual change due to Finnish consonant gradation) + -lta
  → turvallisemmalta

So the -mm- comes from the way the stem behaves when you add case endings to the comparative, and -lta is the ablative ending required by näyttää in this kind of meaning.

How does tie näyttää turvallisemmalta differ from just saying tie on turvallisempi?

They are close in meaning but not identical:

Tie näyttää turvallisemmalta.
= The road looks/seems safer.
→ This talks about appearance or impression; maybe visually, because the fog is gone.
Tie on turvallisempi.
= The road is safer.
→ This states it as a more objective fact or comparison.

In this context (fog disappearing), we’re emphasizing how the road appears to us, so näyttää turvallisemmalta is more precise and natural.

Could you also say Kun sumu katoaa ja lämpötila nousee, tie näyttää heti turvalliselta (without comparative)?

Yes, grammatically that’s fine, but the meaning changes slightly.

turvalliselta = safe
turvallisemmalta = safer

Original:

tie näyttää heti turvallisemmalta
→ the road immediately looks safer (than before / than it did).

Alternative:

tie näyttää heti turvalliselta
→ the road immediately looks safe (in general, simply safe).

The original with turvallisemmalta highlights the change: it becomes safer once the fog disappears and the temperature rises.