The probability that it "be" or "is" -- subjunctive?

I am writing a scientific paper, and therefore I would like to be as precise as possible with language too. Following the subjunctive mood, I know for example that the following is correct:

"Is is important that she be at home by 9 p.m.".

It does not sound so weird to me when the subjunctive is used with the verb to be.

However:

"The probability that temperature exceeds its historical maximum is large."

sounds to me better than

"The probability that temperature exceed its historical maximum is large."

Which one is correct? Is it a matter of taste?