"The temperature now is about 15 degrees."

Translation: 现在的温度大约是十五度。

[wmprusinski]

Why use 大约 and 是 together like this?

[NasuSamaruk0]

大约/大約 together with 是 means "about". Without 大约/大約, the sentence excludes "about".

[kokaku]

is 的 optional?

[KX3.]

Yes it is.

[KX3.]

温度现在大约是十五度。was marked wrong, reported!

[garpike]

I just typed this and it is now accepted.