General it as Subject
4 it V nThe verb is followed by a noun group. In the case of be and come, the noun group is the Complement; in the case of be blowing, it is the Object.
There are three verbs with this pattern.
be be blowing come
It was four o'clock in the morning.
We get called out in all weathers - usually when it's blowing a gale.
When it came time to think about a new career path, he was at a loss.