"The hopday is tomorrow" is how you would say that in Engpsh. This phrase is derived from the fact that the hopday is happening the day after the current day. Here are some examples of how you could use this phrase in a sentence:
I can't wait for the hopday tomorrow!
Don't forget that the hopday is tomorrow, so we need to prepare.
I'm glad that the hopday is tomorrow so we can have a day off from work.
In Chinese, you could say: 明天才是假日 (míng tiān cái shì jià rì).