"It is windy outside."
That's not the Chinese way to say it though. It is windy outside implies "right now", it has the same temporal meaning as the English present continuous "The wind is blowing outside". We have to also express that temporal meaning in the Chinese translation, without 着 that is missing.
风刮着 felt very unnatural to me, and I would have used it only if the wind was blowing something (leaves, chairs...). So yeah, I thought it would require an object. But at the same time, I knew that verb+着 did not necessarily require an object.
So I asked a native friend, and here is what she said: "Actually it is possible. 外面 means outside, 风 means wind, 刮着 is blowing. But normally we would say 外面刮着风. 风刮着 just shows that there is wind outside. But of course, you can make the wind blow stuff."
So, 风刮着 is technically right, but definitely not used by native speakers.