Sıcaklık on derece.

The temperature is ten degrees.

Breakdown of Sıcaklık on derece.

• olmak: to be
• on: ten
• derece: the degree
• sıcaklık: the temperature

Questions & Answers about Sıcaklık on derece.

Why is there no verb “to be” (is/are) in Sıcaklık on derece?

Turkish omits the present‐tense copula in simple nominal sentences. In English you’d say “The temperature is ten degrees,” but in Turkish the “is” is understood and dropped. If you want a more formal or written style you can add the suffix -dir:
Sıcaklık on derecedir.

Why is derece not plural (dereceler) after “on” (ten)?

In Turkish, when a noun follows a numeral, it remains in the singular form. You say iki kitap (“two books”), not iki kitaplar, so likewise on derece, not on dereceler.

What grammatical case is derece in here?

It’s in the default, unmarked nominative (or “zero case”) because it’s part of a nominal predicate. Numeral + noun constructions don’t take a case ending on the noun when they express quantity or measure.

Why don’t we see the suffix -dir on derece?

The suffix -dir is the formal copula marker that you can use for equational statements, but in everyday speech it’s usually omitted. Both are correct:
informal: Sıcaklık on derece.
formal/written: Sıcaklık on derecedir.

How would you say “The temperature is not ten degrees”?

You can negate the predicate with değil (informal) or değildir (formal):
Sıcaklık on derece değil.
Sıcaklık on derece değildir.

How do you ask “What is the temperature?” in Turkish?

Use kaç derece (“how many degrees”) with the subject:
Sıcaklık kaç derece?
You can also specify “air temperature”:
Hava sıcaklığı kaç derece?

Could I switch the order and say On derece sıcaklık?

That inversion sounds odd. Turkish is a topic–comment language, so the topic (sıcaklık) comes first, followed by the comment (on derece). Reordering it loses the expected flow and may confuse listeners.

How do I express negative temperatures, like “ten degrees below zero”?

Prefix the numeral with eksi (“minus”):
Sıcaklık eksi on derece.
You can also say sıfırın altında on derece (“ten degrees below zero”), but eksi on derece is more concise.