It's snowing heavily

Since this morning it has been snowing across a wide area of Japan. 
It took me extra 30 minutes to get to my office.
Yesterday, the weather forecast said the highest temperature, in the vicinity of around my office, would be 3 degrees celcius today.
As he said so Like it said, I feel it's so cool cold outside that I don't want to go out of leave my office.
But I have to go out for my lunch. I hope it stops snowing when before I go home.

RED = corrections or inserted words

BLUE = words which I have moved

I hope it stops snowing before I go home

or

I hope it has already stopped snowing when I go home.

It's snowing heavily

Today it has been snowing in a wide area of Japan since this morning.
It took an extra 30 minutes to get to my office.
The weather forecast said yesterday that the highest temperature around my office today would be 3 celcius.
As he said so, I feel that it's so cool outside that I don't want to go out of my office.
But I have to goet out for my lunch. I hope it stops snowing when/before I go home.

It's snowing heavily

Today it has been snowing in wide area of Japan since this morning.
It took extra 30 minutes to get to my office.
The weather forecast said yesterday the highest temperature around my office today would be 3 celcius.
As he said so, I feel it's so cool outside I don't want to go out of my office.
But I have to go for my lunch. I hope it stop snowing when I go home.

It's snowing heavily today

Today, it has been snowing in a large area of Japan since this morning. 
It took an extra 30 minutes to get to my office. 
The weather forecast said yesterday that the highest temperature around my office today would be 3 Celsius. I think they guy was wrong, I felt so cold outside that I didn't want to get out of my office. But I had to get my lunch. I hope it will stop snowing before I go home.

NOTE: The english language like many others, require a specific way of saying and phrasing things around.  An American person will say your words similar to what I wrote.  Good try!

It's snowing heavily

Today it has been snowing in a wide area of Japan since this morning.
It took an extra 30 minutes to get to my office.
The weather forecast said that yesterday the highest temperature around my office today would be 3 degrees celcius.
As he said, its so cool outside that I don't want to go outside.
But I have to go for lunch. I hope it stops snowing (before/while) I go home.