Why is the weather the only reason for the cancellation delay of Air China flights?

Well, it's definitely not just Air China flights that are affected. It may be that Air China has more flights in the local area, so there are more flights affected, so it gives the impression that Air China will cancel more flights. In addition, even if the origin and destination are the same, some companies can fly and some companies can't. There are usually two reasons for this. One is that when the weather is bad, there is a large backlog of flights. After the weather is fine, planes will have to queue up for take-off and landing. If they are behind, they will have to wait for a long time. The other is that when the weather is bad, the incoming plane can't come, so the return flight can't fly.